Tenjin was explaining to Jirou how to solve a problem last chapter, and Akira reminisced about how they meet. So othis flashback is absolutely on point. I think Kanamaru-sensei will show us the differences between both in the eyes of Akari, and how she loves Jirou more.
Or, they might show us how Jirou falls in love with Tenjin for helping him pass the university exams, how handsome and good guy he is, making this manga a convoluted BL story ¯\(ツ)/¯