Senjuushi: Kijuushi-tachi no Happy Birthday!
· 千銃士 貴銃士たちのハッピーバースデイ!
Synopsis
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.
Studios: TMS Entertainment
Source: VIDEO_GAME