I activate polymerization and wild fan speculation! (Sorry I'm bored you don't need to read this it's mainly a joke)
Joke speculation No.1 Kourin and Aichi eloped into another dimension due to Kourin carrying Aichi's daughter
Joke speculation No.2 All this time Aichi was actually female and Kourin was just a fragment of her being. I mean come on what kind of boy wears turtle neck sweater UNDERNEARTH a jacket or vest
Joke speculation No.3 Aichi new role model/BBF is Sasuke Uchiha
Joke speculation No.4 This entire season was made because Bushiroad just realized they didn't make a good MC and switch it to the most favorite character