Takayuki Narumi starts as an ordinary, initially adrift high school student at Hakuryo Hiiragi Academy. He first notices Haruka Suzumiya in a bookstore before their third year, though their connection only develops later through mutual friend Mitsuki Hayase. After Haruka confesses, he accepts despite no initial romantic feelings, gradually coming to care for her. Their relationship moves slowly until Mitsuki's birthday, where his delay causes Haruka to be hit by a car while waiting at a transit station, plunging her into a coma.

Following the accident, he sinks into deep depression, fixating on hospital visits while abandoning his education and future. Banished from visits by Haruka's father, he is forced to face reality. During this bleak period, he forms a co-dependent bond with Mitsuki for mutual emotional support, working part-time at the Sky Temple restaurant. His core indecisiveness and avoidance of hard choices become pronounced, often deferring to others' expectations.

When Haruka awakens three years later with anterograde amnesia, he joins her family in concealing the elapsed time to shield her fragile state. In the OVA narrative, he ends the relationship with Mitsuki to recommit to Haruka. Their renewed bond falters when Haruka, fearing she burdens him, abandons him on a departing train. This separation drives him to pursue stable employment amidst economic hardship while Haruka focuses on university entrance exams for her picture book author dream. His job search signifies a new sense of responsibility, contrasting his earlier passivity.

Persistent traits include difficulty making impactful decisions, a tendency toward self-blame, and retreat into lethargy when facing emotional fallout. Yet, his commitment to supporting Haruka's aspirations and securing employment indicates gradual maturation. The OVA concludes with their paths converging as both work towards individual goals while sustaining their connection.