Senjuushi: Kijuushi-tachi no Happy Birthday!

Senjuushi: Kijuushi-tachi no Happy Birthday! · Episode 1 · “Senjuushi: Kijuushi-tachi no Happy Birthday!”

The OVA will tell a "heartwarming, hilarious slice-of-life story" about the noble musketeers holding a surprise birthday party for Master on a certain day after the events of episode 6.