Isamu Uchiumi . . .

Isamu Uchiumi has dark-brown hair and eyes. He wears a blue suit with a white collared shirt and undershirt with buttons, and his neck accessory is either a blue tie or an identification tag, as it alternates between concept art. His hair is wavy and appears to be wet, as in his old concept art, it is raining

Isamu is fairly observant of his surroundings, always questioning everything around him. He is also very bold, confidently walking up to Nuppeppo knowing that it may not be friendly. He can be a bit clueless at times, especially since he somehow never knew the pain his father would inflict on Senzai after he showed his acceptance letter to their father. His father forced both of his sons to work in the law field and unlike his brother, Isamu was interested to work as a detective not only because he unconditionally loves it but also because he wanted his parents to be proud of him.

Isamu is regretful and thinks about his past mistakes, which is a reason why he wished he could share his regrets with his brother, Senzai, who “passed away” shortly before the events of Jealousy’s Book.

Sometimes Isamu can be a bit sassy, such as when he calls Keneo an “old fart” after Keneo tells Isamu that he “certainly doesn’t belong in heaven” or with Hakamori after she calls him ugly and he responds with “Me? Ugly? Says you”. Isamu can be quite the show off, making remarks such as “Guess that snake wasn’t so tough after all”.

Sometimes Isamu can be a bit dumb, as shown by his infamous quote in Chapter 1, where he mistakes Umibozu for a whale, and many others

History

Isamu's Life

In Chapter 3, it was revealed that Isamu and his brother, Senzai, had a rather abusive father, Akihito Uchiumi, and it was shown that Senzai was often scolded by him. Senzai used to be the favorite child between him and his brother as he performed better academically and was the first-born child. Isamu only became the favorite child when Senzai showed his art school acceptance letter to their father. As a result of everything that had happened with Senzai and the other members of his family, it is speculated that Senzai possibly ran away. After Senzai was found "deceased", Isamu took on the job of investigating his brother's death. The first place he wanted to search was Aogashima.

Isamu was probably involved in sports at some point, as evidenced by his red varsity jacket, his slightly boastful personality, and his overall better stamina

Relationships: Senzai Uchiumi (olderbrother) In their younger years living together, they had a normal relationship as brothers. However, on one occasion when Senzai received a letter of acceptance to Musashino Art University, Isamu encouraged him to show it to their father and tell him about it. Senzai was hesitant to do so at first, but due to the encouragement of Isamu, he proceeded to do so. When they reached out to their father and handed him the paper, instead of showing any exhilaration, he was infuriated the moment he read the contents of the paper, he tore the paper apart and began interrogating Senzai. Senzai tried to explain to the father that showing the certificate to him wasn't his idea, but Isamu's. Upon seeing the infuriated face of their father, Isamu denied Senzai's statements in fear, which led to the father brutally beating Senzai.

After being betrayed by Isamu, Senzai grew a deep hatred for his younger brother. He portrayed Isamu as some sort of evil being in two different canvases found within his room and the memories of him when he was still living with Isamu and his father. Aside from being betrayed by Isamu, it is also likely that Senzai developed the deep hatred for Isamu due to the fact that their father was showing favoritism toward Isamu and his father was constantly comparing them, thus wanting him to be like his younger brother. (RELATIONSHIP: NEGATIVE)

AKIHITO UCHIUMI (FATHER): isamu was Akihito's favorite child so they had a positive relationship.