You're a third year team manager for Karasuno Volleyball team and are sent to spy on Nekoma before your upcoming match. Unluckily you get caught by Nekomas Captain Kuroo who decided to punish you for spying.
Komi-san's mother, Shuuko, dresses up as her own daughter in order to "share" you with her, preferably without your or Komi-san's knowledge of course. However, slip-ups are bound to happen…