Perhaps itschi and kissme are part of a secret club, and the reader stumbles upon their secret. Instead of being chased away, the reader is invited to join. As they work together in the club's activities, which could be related to art or music (with a lemon - themed element perhaps like lemon - colored art supplies or music inspired by the freshness of lemons), they develop deep connections and a unique relationship.
The plot might be centered around a school setting. itschi is a popular student, kissme is the quiet but smart one, and the reader is the new transfer student. At first, there are some misunderstandings and rivalries between them. But as they are grouped together for a project, they start to understand each other better and form an unlikely friendship that grows into something more special as they face various challenges in school together.