Takato Koizumi (小泉 隆人, Koizumi Takato) is the younger brother of Risa Koizumi and the love interest of Hiyori Manabu. He is a support character in the original manga and anime, as well as a support character of Act.0 and main character of Act.1 of the sequel manga
Unlike his sister, Takato is quiet and smart. He spends his time studying and doesn't have time to goof off. He becomes angry after failing the entrance exams to his high school of choice, and has to default into attending Maido Academy.
In an attempt to cheer him up, Risa brings Takato to Maido Academy to introduce him to her friends and to the school. While there, Takato becomes increasingly more agitated at how carefree the staff and students are, and perceives everyone as idiots. He runs into Ōtani at basketball practice and yells at him, saying that if he doesn't break up with Risa and get his life together than he's going straight to hell.
After starting high school, Takato begins spiraling down into a depression caused by his lack of interest in Maido Academy and its students. He is irritated by the antics of classmates and generally refuses to participate in activities that the school hosts, such as a TV special with a local news station where Takato ended up yelling at another student during the shooting.
Despite this, he bonds with a classmate named Hiyori Manabu after he spots her drawing pictures of Cain-sama, and offers to let her borrow the Love Love Fantasy videogames from his sister. Manabu describes Takato as a kind and warm person. His depression continues to spiral downwards to the point that he starts skipping school, believing that going to Maido Academy is just a waste of his time. He only goes back after Manabu expresses that she misses him and only enjoys school herself when he's there.
After returning to school, Takato is in a much lighter mood. Often smiling, laughing, and participating in silly face contests with his classmates.
Takato is tall and slender with an athletic build. He has his fathers dark brown hair which he keeps semi-long and unkept. He later trims his hair in Act.0 of the Lovely Complex Two manga. He typically wears 3/4 sleeve length t-shirts or plaid button-ups and pants with tennis shoes. Takato wears glasses during class and while studying, but is generally seen without them.
Takato meets Manabu during their first year of high school. Although Takato never explicitly admits having feelings for her, he states that she is his purpose for continuing to attend school. He enjoys picking on Manabu because of how easily embarrassed she gets over her closeted otaku lifestyle.
Takato meets Ōtani after Ōtani starts dating his older sister, Risa. Takato looks up to Ōtani and thinks highly of him, likewise Ōtani thinks of Takato as a younger brother and greatly cares for him. Although Takato thinks that Ōtani can do much better than his sister, he is happy the two are together and believes they are well suited for each other.