Hahaha. As I thought, Atohira will become a love rival.
Also, btw, the line where Atohira and Koharu on their first scene they are in together here, if I'm not mistaken, (since I learnt a bit of Japanese, I kinda know it because of the raws) when Koharu was offering the tickets, Atohira actually said "Ii" which means "it's fine" and another meaning of "don't bother" which is why Koharu apologizes.
But I wonder what will happen next. If Atohira will remain his aloof attitude towards or move forward with his feelings.