Moonlight Jellyfish (2004)

Seiji has to look after his brother Michio who has Xeroderma Pigmentosum, a desire that is fatal if exposed to sunlight. Also, Michio, is equal to that of a child. Seiji is forced to join the Yakuza and work through the ranks. But one night, Seiji saves a young woman from a drunk pervert who happens to be Michio's nurse.