H₂O's tale revolves around Takuma Hirose, a junior high school student who is visually impaired. The reason behind his disability remains unknown. Following his mother's untimely demise, he becomes emotionally scarred, transforming into a solitary and introverted person. Eventually, Takuma and his father relocate from the city to a rural area where he enrolls in a new school. Here, he encounters several girls, but his deepest relationships develop with three of them: Hayami Kohinata, a determined and resolute girl; Hinata Kagura, a kind and accommodating young lady; and Otoha, an enigmatic and vivacious character.
