Haruto Kirishima hails from rural Hiroshima Prefecture, initially reserved and shy. He carries a long-unrequited affection for his middle school classmate Nanami Kanzaki, often watching her from afar without confessing. His life shifts dramatically when Yuzuki Eba, the daughter of his father's acquaintance, moves from Tokyo into his family home. Though initially irritated by this arrangement and unaware of their childhood meeting at a summer festival where he comforted her, Haruto slowly develops a protective instinct toward Yuzuki, forging a close friendship. Yuzuki's influence helps him become more outgoing, empowering him to finally confess to Nanami. However, Nanami rejects him, citing his consistent prioritization of Yuzuki's needs over their relationship, like missing a date to help Yuzuki with family issues in Tokyo or retrieving his sister Harume instead of staying with Nanami. This pattern underscores Haruto's strong sense of responsibility and consideration for others, traits that frequently lead him into misunderstandings or troublesome situations. He struggles with intimacy, often averting his gaze or reacting abruptly to avoid complications. After Nanami's rejection, Haruto realizes his feelings for Yuzuki and confesses. They start a long-distance relationship when she returns to Tokyo. When Yuzuki abruptly cuts contact and sends a "Dear John" letter mentioning a new boyfriend, Haruto becomes deeply depressed, suspecting she is in trouble rather than having moved on. Determined to uncover the truth, he transfers to a Tokyo high school, moving into his sister Aoi's apartment in the Ayano dormitory. There, he befriends Asuka Mishima and Kyosuke Kazama, later discovering Kazama is Yuzuki's new boyfriend and is terminally ill. Haruto confronts the situation by openly declaring his intent to win Yuzuki back, issuing a "declaration of war" against Kazama. Kazama undergoes risky surgery to prolong his life for a fair competition but dies post-operation due to physical stress. Grief-stricken, Haruto and Yuzuki agree to part ways. In the following months, Haruto grows closer to Asuka and eventually accepts her confession after she issues an ultimatum. They date for roughly a year and a half. A chance reunion with Yuzuki reignites Haruto's unresolved feelings, causing him to reevaluate his relationship with Asuka. After repeated encounters and emotional turmoil, he confesses his enduring love for Yuzuki to Asuka, leading to a breakup that strains his friendships. Haruto moves into his own Tokyo apartment. When Yuzuki runs away from her disapproving family, he invites her to live with him. Despite opposition from Yuzuki's father, they reconcile with her family and continue their relationship, navigating adult challenges alongside neighbors like Miyu Hoshina. After graduating college, Haruto takes a job in Kochi while Yuzuki pursues teaching in Tokyo. The strain of their long-distance relationship, compounded by work pressures and exhaustion, causes a temporary breakup. When Haruto is transferred back to Tokyo, they reunite under cherry blossoms at Toyama Park, rekindle their relationship, and marry. A decade later, they run Kirishima Restaurant in their hometown, raising their son Daiki. Kazama's helmet is displayed in the restaurant as a memento. Throughout his life, Haruto demonstrates exceptional cooking skills, honed through high school cooking club participation, part-time restaurant work, and cooking for friends and family. This passion evolves into his career, culminating in restaurant ownership. His given name reflects "blue/green" (青) and "big/great" (大), while his surname Kirishima means "paulownia island" (桐島).