1-3: manato x mikiya, step brothers. after getting together, they went to hot spring together for to do an amazing thing xxx.
4: youngest brother x his friend.
5: second oldest x his kouhai. he was against gays and his youngest bro's love. but came to accept it when his kouhai opened his heart.
6: the eldest son came back with 2 kids, twins of his own. he revealed to be dating a mafia guy.
Zutto Issho ni Kurashimashou