Midsummer's Equation

Yukawa meets a boy named Kyohei on the train heading to Harigaura. Kyohei is the nephew of the proprietress of Rokuganso Inn. He had come to visit his aunt and uncle by himself during summer vacation because his parents were busy with work.

The next morning, a man is found dead on the rocks below a concrete embankment. The man was Masatsugu Tsukahara, who had also been staying at the inn. Was the death an accident or murder?

Kyohei becomes involved in the case in an unexpected way. Narumi, the only daughter of the innkeepers, devotes herself to preserving the sea of Harigaura. Her parents who run the inn are considering shutting it down because of the decline in the local tourism. And why had Tsukahara come to Harigaura in the first place? As the complicated connections behind the mysterious death gradually begin to unravel, Yukawa discovers the heartbreaking truth lying at the heart of the case.

小学五年级的恭平，被父母安排到亲戚在玻璃浦经营的‘绿岩庄’过暑假。同时帝京大学物理系副教授汤川学，也因海底矿物开发计画，来到这个拥有美丽海景却没落的小镇。隔日，距离绿岩庄四百公尺外的堤防下，发现一具男尸。死者是另一名房客，而且竟是位退休刑警… 交错在海岸边的杀意、亲情、守护、罪恶感…各种人性挣扎，最后，又该由谁付出代价？带着与人命有关的回忆度过余生…