Hotaru Hinase is a high school student who values family and friends above everything else. She doesn't understand romance, so she decides to live without the experience of falling in love. While spending time with her friend at a cafe, Hotaru witnesses a couple breaking up. On her way home, she sees Hananoi sitting alone in the snow. She extends her umbrella to him as a gesture of kindness. The next day, Hananoi asks Hotaru to be his girlfriend. Despite rejecting him, he continues to be near her and does selfless acts to please her. As a result, Hotaru experiences emotions she never felt before. Believing that these emotions could develop into love, she agrees to date Hananoi.
Hananoi-kun to Koi no Yamai has been published digitally in English as A Condition Called Love by Kodansha USA since March 3, 2020.In 2021, the series won the 45th Kodansha Manga Awards in the shoujo category.