Miyauchi' birth mom was a beta who was maid of miyauchi's alpha mother. So they had a relationship to which beta mom got pregnant. But the aloha mom doesn't know. They both got separated cuz alpha mom have go marry someone high class. Which was jirou mom. So miyauchi is son of beta mom and alpha mom and that alpha mom and alpha dad had jirou.
Jirou and Miyauchi share Jirou's mom.
Jirou's mom ((alpha)) had relations with Miyauchi's mom ((beta)) but had to go marry Jirou's dad, Tarou. Jirou's mom is now off with her fated pair/soul bond and no longer married to Tarou I think.
Miyauchi's father is related to Jirou
can someone explain how miyauchi and jirou are blood related? i didnt get the last part of vol1