Kimi no Saigo no Ikkagetsu, Koi wa Opal-iro ni natte

Tomoya, a high school student, grows closer to his childhood friend Ayano after his mother's suicide. As a mysterious illness called the "black lump disease" spreads online, the two decide to spend their summer break traveling by train with no fixed destination. Along the way, they share personal struggles and hopes, with Ayano making a list of things she wants to experience. Though Tomoya takes time to admit his feelings, the two eventually become a couple. However, their time together is limited, and Tomoya remains unaware of the difficult reality that lies ahead.