A Siren in Midsummer

When Yuuya (優弥), Harumi (春海), Ryou (遼), and Takafumi (崇文) went camping together as high schoolers, Yuuya suddenly announced “I will secretly confess to someone here”, but afterwards, he fell off a bridge and died. Ten years later, the three people who met up at a class reunion suspect each other of being Yuuya’s murderer. The one who was accused exposed his relationship with Yuuya; the three each had in common some kind of secret memory…who was it that was with Yuuya on the suspension bridge that day? In the end, who was the one that Yuuya liked? (Translated from Chinese via Tongli Publishing - unable to confirm names given multiple potential readings of kanji)