Nidome no Natsu, Nidoto Aenai Kimi

A boy reflects on a summer when he lost someone significant to him. He had developed feelings for Moriyama Rin, a girl with an incurable illness who concealed it during high school. Their final moments together occurred at a cultural festival, after which Rin passed away. Before her death, he confessed his feelings, something he now regrets. He found a note from her that simply said "I'm sorry." Guilt and self-blame led to a time leap, bringing him back to the moment he first met her. Now given a second chance, he resolves not to express his emotions, determined to keep her happy for the remainder of her brief life.