Naomasa Tsukauchi

Naomasa Tsukauchi is a police detective in the Police Force.

Appearance
Naomasa is a tall man with short black hair and black eyes. As a member of the police force, he is normally seen in his uniform. He wears a signature tan overcoat and a matching hat. He also sports a black suit underneath with matching slacks and dress shoes.

Personality
Detective Tsukauchi is an earnest, hardworking individual who has earned the right to be a close friend of All Might. Enough so, that he was even entrusted with the truth about One For All. He appears to have a close relationship with All Might, as he even leaked sensitive information to the hero just because he felt it was the right thing to do.

Unforeseen Simulation Joint Arc
Outside U.A. High School, Naomasa checks the status of Class 1-A and determines that everyone (except Izuku Midoriya) is unharmed. He then tells Class 1-A to head back to their class. Tsuyu Asui asks him the condition of Shota Aizawa, to which he replies that he is in a critical state but not life-threatening and says that although Thirteen and All Might are injured, they are not in a critical state and are being treated by Chiyo Shuzenji. Naomasa then asks Nezu whether he can investigate U.A., which the principal allows.

Naomasa then visits U.A.'s Nurse Office, friendly greeting All Might. All Might asks him about the status of the students as well as Thirteen and Shota, to which Naomasa states that the students are fine and the teachers are not in life-threatening danger. He then says that if he, Thirteen and Shota had not fought the villains, the kids would probably be in a terrible condition, but All Might says that the students also fought bravely and made those villains look like fools and concludes that they will make fine heroes which Naomasa smiles to.

U.A. Sports Festival Arc
In a meeting with U.A.'s staff, Naomasa tells them that he has investigated the villains Tomura Shigaraki and Kurogiri but could not find any information about them. He then says that they captured and arrested 72 villains at the USJ and says that they were all third rate thugs, however, the problem was that all of them seemingly swore allegiance to Tomura. Naomasa insinuates that in an age filled to the brim with heroes, villains must have felt pressurized and that is why they decided to follow Tomura's "innocent" simple-minded brand of evil. Naomasa says that he is going to assist in enlarging the police force so that they can continue capturing more criminals.

Vs. Hero Killer Arc
Naomasa meets with All Might at U.A. He tells All Might that the Police Force have tried everything to get information out of Nomu, however, everything they tried did not work. Naomasa says that they instead looked into Nomu's background through DNA analysis and have discovered that Nomu was once a human with a criminal record. Naomasa explains that the DNA analysis also revealed that Nomu has the DNA of at least four different humans mixed with his own. Naomasa concludes that Nomu is an artificial human made to measure up to multiple Quirks and that having all the DNA in his body as well as his body modified caused Nomu's brain activity to stop. Naomasa tells All Might the real issue is that Nomu's DNA is of primary concern because it contains multiple Quirks. Naomasa says that Nomu could not have acquired multiple Quirks in any way (unless Nomu acquired the Quirks through advanced genetic familial permeation. Naomasa comes to the conclusion that someone with a Quirk that can grant Quirks is behind Nomu's acquisition of multiple Quirks.

School Trip Arc
After incident at Kiyashi Ward Shopping Mall. Naomasa arrives at the scene and takes Izuku to the Police Station to be questioned by him about the event that transpired. At the Police Station, Naomasa questions Izuku about Tomura and their conversation. Although the information Izuku provides is nothing new, Naomasa thanks Izuku for the information and praises Izuku for being level headed during his confrontation with Tomura; The Police investigator is glad with Izuku's actions because collateral damage was kept to a minimum and no lives were lost.

Outside the Police Station, All Might greets Izuku and Naomasa; he apologizes to Izuku for not being there. After All Might answers Izuku's question and Izuku along with his mother leave, Naomasa theorizes that Tomura will probably target other students and decides that Hero schools must exercise more caution and become more proactive in implementing counter measures against villains. Naomasa advises All Might that leaving U.A. is also an option, but All Might decides against it. Naomasa concludes their conversation by saying that they will capture All For One this time, to which All Might agrees.

Hideout Raid Arc
One day after Katsuki Bakugo is captured by the League of Villains' Vanguard Action Squad, Naomasa phones All Might to inform him that they have tracked down the League of Villains' hideout.

A day later at night, Naomasa along with the Police Force and a large number of Pro Heroes wait near the League of Villains' hideout. Naomasa reminds the Pro Heroes of the importance of the rescue operation, that the Hero Society may fall if they do not succeed. Naomasa states that they know the hideout Katsuki is in and tells the Pro Hero team that while investing their efforts in rescuing Katsuki, they will capture the other hideouts to block off the League of Villains’ escape route and then apprehend the villains themselves.

The time for the pro heroes and the Police Force to initiate the rescue operation has come; Naomasa tells everyone that the rescue operation is a battle of speed and to not let any villains retaliate. Naomasa reveals that U.A.'s public apology broadcast was to deceive the villains into thinking that the heroes were having a hard time and could not afford to attack today; thus the pro heroes and the Police Force have the element of surprise on their side for their counter attack since the League of Villains are not expecting them to attack now. The pro heroes and the Police Force head out and stand in front of the League of Villains' hideout, preparing to storm the place.

The pro heroes storm the League of Villains hideout and apprehend Tomura and his fellow villains while another group of pro heroes infiltrate and take control of the League of Villains' warehouse. However, All For One intervenes and summons multiple Nomu while Tomura and his fellow villains escape. Naomasa and the pro heroes deal with the Noumus while All Might goes to chase after All For One. Eventually, they manage to apprehend all Nomus.

After All Might defeats All For One, Naomasa and Gran Torino visit All Might in hospital. All Might who is bandaged and recovering states that he can no longer use One For All and that although he can no longer be the Symbol of Peace, he still has things to do. Naomasa is in disbelief that Tomura Shigaraki is Nana Shimura's grandson. On that topic, Gran Torino comments that Nana Shimura and her husband had a child. However, after her husband died due to heroics, Nana sent her son to a foster family so that he can stay away from the world of heroics. Nana then informed Gran Torino and All Might to not get involved with her son. All Might wishes to find Tomura, however, Gran Torino tells All Might that he is in no position to help Tomura since he has would not be able to see Tomura as a villain. Gran Torino and Naomasa decide that they will handle the search for Tomura. Gran Torino suggests to All Might that he must remain at U.A and carry out what he must still do; helping his successor, Izuku Midoriya.

All Might
Naomasa is a good friend of All Might and one of the few people that knows about the hero's condition. He also takes care of All Might's file work.

All Might thinks he is the best cop there is, which shows how much faith he has in him.

Naomasa and All Might first met while All Might went under the guise of Toshinori (in base form) was posing as All Might's contact, in recommendation of Naomasa's chief. While they were having a conversation in a café, Toshinori constantly made excuses and run to perform quick deeds as All Might. When Toshinori accidentally returns with the uniform still visible (revealing his dual identity as All Might), Naomasa calls him out on not filing reports on all of his heroic activities (as customary of a Professional Hero). Taking pity on the number 1 Hero, Naomasa offered to file the reports himself, letting All Might act without any worries apart from telling Naomasa what he was doing. They have since remained good friends with Naomasa being one of the few individuals that Toshinori fully trusts and can confide with.

Professionally the two also have a special relationship with Naomasa revealing information directly to All-Might on matters such as All for One and Nomu.

Trivia

 * According to the official twitter, his Code Name is "True Man".
 * Naomasa's favorite thing is baseball.
 * the kanji in Naomasa Tsukauchi, Nao "直"(lit. straight) and masa "正" (lit. correct, justice, righteous). Tsuka "塚" (lit. mound) and uchi "内" (lit. inside, within).