A man who had no hope in life jumped into the river, entered the ABO world outside the world, and became the younger brother of the male protagonist (not related by blood). The man was adopted by the male protagonist's parents, and went to the same high school as the male protagonist. However, the man came through the river on the day when the male protagonist's younger brother woke up from a vegetative state. Readers are asked to read on their own.
Purpose: Live hard and seek nothing else