Yoshiteru Zaimokuza is a second-year Sobu High School student suffering from "eighth grader syndrome" (chuunibyou), marked by delusions of grandeur and roleplaying fantasies. He possesses a distinctive appearance: grey or white hair in a short ponytail, glasses, and a tall, slightly overweight build. He constantly wears a trench coat over his uniform and black fingerless gloves, regardless of weather, leading to perpetual sweating. Bullied before high school for his size and chuunibyou interests, Zaimokuza's condition worsened upon entering Sobu High after Hachiman Hikigaya noted his surname's similarity to historical shogun Ashikaga Yoshiteru. This cemented his delusional behavior, including third-person self-references, grandiose speech like a movie narrator, and crafting fantasy scenarios involving peers. The student body widely perceives him as eccentric, "weird, gross, and creepy," resulting in his loner status with few friends beyond arcade acquaintances. Zaimokuza passionately aspires to become a light novel author, game writer, and marry a voice actress. Despite his writing drafts being frequently criticized as "trash" by the Service Club, he exhibits unwavering dedication. He acts like an established professional, submitting scripts for events like Class 2-C's Cultural Festival play. He briefly considered game development but abandoned it upon learning companies would own his creative rights. He displays notable resilience, quickly rebounding from criticism by Yukino Yukinoshita or Hachiman, who terms his enthusiasm "writer's syndrome." Though often physically awkward, Zaimokuza demonstrates unexpected strength during school events. At the Athletic Festival, he devised the "Chiba Shouldertop Engagement" with Ebina Hina and executed the "Zaimokuza Crusher," overpowering opponents to topple a bo-taoshi pole. He also competed effectively in a judo tournament alongside Hayama Hayato and Hachiman, winning matches utilizing his size, strength, and sweat-slicked grips. Beneath his chuunibyou facade, Zaimokuza reveals complexity. He occasionally drops the roleplay to deliver pointed critiques, such as highlighting Hachiman's hypocrisy about their friendship. He values his sporadic Service Club interactions as rare genuine connections. He experiences jealousy toward popular students like Hayama and struggles to interact with girls, often fleeing social situations involving them. When United Gamers Club members belittle his creative aspirations, he retorts, "I write because I love it," emphasizing intrinsic motivation over professional validation, a declaration that momentarily impresses Hachiman. Later narrative arcs highlight his vulnerability and growth. He endures periods of isolation when ignored by peers, including exclusion from outings. Academically, he surprises Hachiman by selecting science courses for his third year, citing fewer female students as a relief given his social anxiety. However, he later recommits to writing during a Service Club career consultation, inspiring a student newsletter. By the series' conclusion, he maintains his chuunibyou persona with increased self-awareness, balancing dreams with pragmatic compromises. Zaimokuza shares a complex relationship with Hachiman, whom he considers a friend despite Hachiman's frequent denials. Their history includes partnering in gym class due to mutual social exclusion. He admires Saika Totsuka, often attempting to involve him in cosplay scenarios. He is nicknamed "Chuuni-chan" by Yui Yuigahama and Komachi Hikigaya, "Za Za Mushi" by Ebina, and "Snowflake" by Komachi.