The literature club is on the verge of losing its room, as student council president Yukino Minekawa threatens to take it away due to their lack of activity. In an effort to save his beloved clubroom, second-year student Shuu Yagi, the only remaining club member, plans to write something for the upcoming cultural festival—yet he fails to come up with an idea. Luckily for him, a solution presents itself in an unusual encounter.

Shuu begins to receive diary entries from a mysterious girl named Eina, who mistakes a chatting app for a diary. He silently observes the incoming messages until Eina sends an alarming diary entry, saying she wants to commit suicide. Out of impulse, Shuu replies and proposes she assist him in his writing. This startles Eina, but she willingly accepts the offer.

Now that Shuu has found someone to write for him and Eina a reason to live, this mutually beneficial proposal marks the start of their newfound relationship. However, there seems to be more that connects these two unlikely individuals than they initially realize.