Outward personality
Takuto Maruki is a counselor who comes to Shujin Academy after the Suguru Kamoshida incident. He's friendly with everybody at the academy, and welcomes the students to talk whenever they have time. He's an extremely patient person, and is good at conversing with others. He's alert and quick to pick up on minor comments made by others. This helps his patients open up to him, as well as allowing them to feel more comfortable. He's clumsy and prone to messing up in comedic situations, unlike the other teachers at Shujin. According to Shibusawa, he tends to charge into things and is quite impulsive. He's popular with teentage girls at the academy, as they constantly state how much they love him and want to be around him.
Maruki asks Akira for help on his research paper regarding cognitive pscience, and after agreeing, he states that he's thankful for the help. His confidant consists of setting up scenarios and asking questions while seeing and recording the answers.
Cognitive Pscience
Maruki is a college graduate who had studied psychology. He heavily studies cognitive pscience, which involves delving into a person's subconcious and helping them deal with trauma through mental and emotional change.
Near the end of Maruki's confidant in November, he finishes his paper, and you celebrate with him. He gives a goodbye speech, as well as meeting with Akira to tell him that he's thankful for his help, and that he couldn't have done it without him. He states that he has his support as a student, and as a Phantom Thief.
Akira is surprised at fist, but calms down after learning that Maruki is okay with it. He ends the conversation by saying that he's sure that they'll meet again. They do, although it isn't in a way that Akira or the Phantom Thieves could ever predict.
After turning his work in, he was told that without funding or a way to back up his claims, his work would be shelved. Feeling dejected, he started using the power of Actualization to change others' realities. Although he thought this was for the better, it stopped others from being able to grow and develop mentally.
The New Year Bringing Back the Dead?
On December 24th, Akira discusses turning himself in with Sae, as they need evidence agains Shido to send him to jail. If the player has maxed Goro Akechi's confidant, he will appear and offer to take Akira's place. Although he's confused, he agrees to let Akechi do it. Goro Akechi is supposed to be deceased. So why is he alive? On Janurary 1st, you wake up to see a man you don't recognize sitting in Leblanc. When you ask who he is, as he seems to look familar, he responds in an almost offended manner, saying, "You really don't know?" Futaba then walks in, wearing her Kimono. She claims that her mother helped her pick it out and tie the ribbon in the back. But that's impossible, as Wakaba Ishiki is deceased as well. You meet with your friends for new years, and start to have a good time..
Ryuji is talking about how happy he is to be back on the track team.
Yusuke is talking about how he's going to spend time with Madarame later.
Haru is going out with her father later.
Ann is excited to go to the mall with Shiho.
Makoto and Sae are going to celebrate the new year with their father.
All of this is impossible, as the track team had been disbanded, Madarame is no longer with Yusuke, Shiho is in physical therapy, and the other two mentioned are deceased.
Akira meets up with Kasumi Yoshizawa and takes a picture with her before walking her back to meet up with her dad. When he says his daughters name, it doesn't feel right, almost as if it's not hers. He lets it go, as he has to figure out what's going on with everybody else.
Nothing seems to be the way it should be, and Akira's suspicions are confirmed when Akechi walks into Leblanc, stating that he needs to talk to him. He asks Akira if he's observed anything suspicious, to which he responds that he has. He and Akechi team up to figure it out, and find the cause together. They run into Kasumi on the way, and take her with, as she wants to know what's happened. They find the cause of the changes being brought upon everybody, which happens to be a palace. They decide to explore the palace the next day, and figure out the answers to their questions then.
Coming back the next day to explore the palace leads them directly to the palace ruler.
Laboratory of Sorrow
Takuto Maruki's true personality is that of a man who was unable to get through his own trauma and grief. If you make it to third semester, you find that he is the ruler of the Laboratory of Sorrow, and is the 9th and final palace ruler in the game. Instead of being a predictable twist villain, he's shown to be a man with great morals who enforces them in a way that the Phantom Thieves believe is bad.
In Maruki's palace you find video-tapes that show important moments in his life that altered him deeply, or show moments of him altering others with his psientific research. You find that deep down, he is a man who was unable to work through his trauma years ago. Prior to the game, it's shown in tape #1 shown by the televison (third cutscene overall,) that Maruki had a fiance named Rumi. They were going to get married and live together, until a home invasion ruined her life on February 3rd. Her parents were murdered, and she was left with crippling PTSD from the incident. He would visit her in the hospital every day, and try to comfort her. After accidentally triggering her by mentioning her parents, he subconciously made a deal with a mysterious entity, who would allow him to change the congnition of others for the better, even if it meant purging memories of people they once cared about. This wiped Rumi of her trauma, but also wiped any memory she had of ever being with Maruki. The tape ends with Rumi asking who he is, and him responding that he mistook this room for his girlfriends', who had "died." As a result of this, he desires to stop anybody else from feeling pain ever again. He believes that all pain must be removed from the world to help people stay happy, ignorant to the fact that pain is what allows people to grow and change.
The first two tapes are about Kasumi Yoshizawa, who is actually Sumire Yoshizawa. You find out in a third tape that Maruki had altered her reality to convince her that she was her dead older sister, Kasumi. Although it's highly debated on whether or not this was the correct or ethical decision to make, it was done. When Sumire finds out, her cognition is fully changed back and she becomes herself again.
Despite his actions being purely out of a desire to help others, he's still changing reality. He's warped the cognition of so many, and the Phantom Thieves have to ask themselves if what he's doing is ethical. Maruki leaves them to decide, as well as letting them choose if they want to stay in his reality or not. They don't. They decide that they need to change his heart, and do so on his "Day of Reckoning," which is February 3rd.
Survey for Treatment
Maruki's palace has a survey that is set up to see who needs "treatment" from him.
All of the "correct" answers to these questions feed into avoidant behavior.
One example would be the second question out of three, which states:
"You're having trouble making your dream come true."
Do you:
A.) Keep up the hard work
B.) Do whatever it takes
C.) Give up for a new dream
Although most would agree that the correct answer would be to keep working at it, Maruki seems to disagree, saying that the correct answer would be to give up and search for a new dream. Maruki thinks that people should completely give up when they face any type of struggle, as he believes that it would put you at risk for feeling anything that isn't complete joy and happiness.
Maruki's Garden of Eden
Once the Phantom Thieves gets to the end of his palace, they get to Maruki's "Garden of Eden."
This garden is beautifully decorated in flowers and tree leaves, full of people filled with artifical smiles from his work. They see Maruki as God. Maruki has gone so far with his work that he develops a full-blown Messiah Complex and seems himself as a God-like figure to others. He wants to be seen as a god, as he believes that he's the closest thing to being one.
There are statues of Rumi everywhere, which shows that even in the deepest part of his own cognition, he's still unable to let her go. This is his ultimate paradise. Everybody is happy. But it doesn't feel right, as it's too perfect. Someone who hasn't been affected by his actualization ability can tell that everything about this reality that he seems to want to implement into the real world is synthetic.
Fight Against Adam Kadmon
Maruki's boss fight is not an easy one. He's got the powers of the god he believes himself to be, and won't hold back againt your team.
Maruki has 5 phases, each one easier than the last. His persona is Azathoth, and he has 5 parts to his first phase. Maruki, Azathoth, and three tentacles. The tentacles heal Maruki and Azathoth, and they regenerate when killed. Wiping the tentacles to attack Azathoth before they regenerate is one tactic that can be used. Once his health drops below a quarter of its full amount, the second phase will start.
In phase 2, Maruki summons more tentacles to make Azathoth appear bigger. His max HP will double, and while Maruki stays the same, he's difficult to defeat due to his high endurance. The tentacles still grant him healing, and he will limit player movement in an almost completely random order. Although it won't happen too often, which leaves a window of time to attack, it's still not good. On harder difficulties, he'll do it twice in a row. Melee and baton passes will be prohibited the second time, and healing will also be locked off the third time. He prohibits guarding on his fourth turn, and any kind of item or support skill on the fifth. Tentacle affinitites also change every turn, so scanning them after every turn helps. Azathoth attacks twice per turn, and spams an attack called Evil Smile frequently. One HP drops low enough, he will start targeting certain members on your team, and start inflicting damage onto them. It's best to have this member guard for the time being, as he will strike that member with Piercing Strike, which is an almighty attack that will surely kill them. Once HP turns critically low, he will use Tyrant's Stance, followed directly by a ban of item use. Guard this, as it will also surely kill your team. If it takes more than 40 turns to defeat Azathoth, he will cast a Megidolaon, which does around 1300 damage, knocking all party members out.
In phase 3, Maruki's persona ugrades to its final form, Adam Kadmon. His persona is unattackable, and Maruki takes heavily reduced damage, and can be damaged by guns in this phase. This phase is easier, as he only has 2 attacks. Origin Light is a severe almighty attack that he uses, but when his HP drops to a quarter if what it was, he uses Revitalize Soul, which heals 300 HP to party members and 1200 HP to himself. After this, he uses Grand Palm, which is an attack that does more damage than what your team should be able to endure. Party members will always endure the first hit. After he's used Revitalize Soul, he takes normal damage.
In Phase 4, Maruki fuses himself with his persona, and attacks from inside of him. His HP is impossible to deplete, and party members can only do damage using ranged weapons. Adam Kadmon will use Attack Position for his first move, which leaves him open to take damage, but his HP threshold is so high that it really doesn't matter. After using Attack Position, he proceeds to use Full Force, which does 1000 damage when unguarded. The party will always endure this attack with 1HP to spare, so it's impossible to lose at this phase. After two turns of this, the fight ends and a cutscene plays of Joker shooting Adam Kadmon where his weakness is.
Phase 5, Maruki has accepted his defeat. He stops Joker from leaving the palace to fight him one last time. They are both unable to use their personas, as the end of metaverse is coming after they leave. Maruki wants to fight Joker one last time so that he has no regrets. During this fight, he vents out the frustrations he had been holding in for years. He addresses his grief and inability to move on from Rumi, and after about 4 turns, the fight ends. Maruki falls and accepts his loss. He tells Joker that he was afraid that they wouldn't wish for the same reality. Just as he's about to fall off of the ledge they were standing on, Joker grabs him to prevent this. The helicopter that the Phantom Thieves are in eventually comes around to save them.
After the Battle
After Maruki's palace, the player doesn't see much of him until the very end of the game when Akira is getting ready to go home.
When the ending cutscene plays, the Phantom Thieves are waiting for him in a van they're in. They notice that people are still looking for him, possibly wanting to get him back in jail. They question what they should do, and they're at a loss until a car pulls up behind him asking if he needs a ride. He turns around to see Maruki sitting in the driver's seat. They agree that it's best to go with him, and he gets in. He drives Akira to the train station, and before dropping him off, he states that he's decided to face his problems head-on and that he's done running away. He wishes Akira a final farewell and drives away after seeing him off with the rest of his friends.
Symbolism
Maruki's palace has a lot of religious symbolism in it. As stated before, he views himself as a messiah, and somebody who is there to fix the problems of others.
His metaverse treasure is a torch, which is usually a symbol of enlightenment, learning, and knowledge. He sees himself as a guide to lead others to their dream reality.
His persona, Azathoth, is known for being a symbol of primordial chaos, as well as being the god of blind idiocy. This was most likely chosen to be his persona, as it symbolizes how Maruki thinks he's doing the right thing, but is blind to the lack of growth he's causing people to have.
His personas' final form, Adam Kadmon, is known for being the first, or "original" man in the teachings of Kabbalah. He is the first of the Four Worlds that came in after contracting God's original light.
The music in his palace has a solemn tone to it, and the speed is similar to the speed of music you would find at a cathedral. You can hear faint chanting in the background of the OST as well.
At the end of the game, it's found that Maruki is a taxi driver. This could mean that he wants to lead people to their preferred destination, instead of picking it out for them based on what he thinks they'd like.
Trivia
Atlus designed Maruki to be a sympathetic, unlike the other villains throughout the game. The design team made sure he never mocked anybody or did anything unfavorable, to keep him neutral.
Maruki's persona is different from everybody elses, as it can be used outside of the metaverse. It is highly unstable in this state.
Maruki is the only palace ruler that maintains his palace without a shadow-self.
Maruki is the only "evil force" that isn't reduced to a shell of his former self when his heart is changed. This is because Yaldabaoth, the ruler of the metaverse, had already been taken down.
Maruki attempts to re-create the famous Salt Bae meme at the schools' cleanup event. However, the salt flies into the air, missing the pot entirely.
Maruki is the third palace owner to be aware of the fact that their palace exists. The other two were Futaba Sakura and Masayoshi Shido.
Maruki is one of the few people who has crossed Masayoshi Shido without facing death.
Maruki is one of the only bosses in the Persona/SMT series that is completely human.