Kimi ga Inakunatta Fuyu no Umi

Shuu and Sena have feelings for each other, but they are afraid to express them. While their relationship is in such a fragile state, a car accident occurs at the beach. Shuu wakes up in the hospital when he heard the sirens of an ambulance in the distance. Ignoring his aching body, he rushes to Sena's hospital room, There he found Sena, who starts calling Hiiragi by his surname, "Kutsuna"?
"I just want to see 'you' once again, by that dazzling sea."
(Source: Printemps Shuppan, translated)
Note: Includes one extra chapter.