It was announced during the final episode of Senjuushi TV anime on Tuesday that an OVA for the franchise will be released on March 6 of next year. According to the official website, the story will be about the characters celebrating their master’s birthday, which happens one day after the sixth episode.
Senjuushi is an anime adaptation of the cellphone game released this March, which anime adaptation was announced at the same time during AnimeJapan 2018. The characters are representative of the guns appeared in the history and souls revived by the master, a.k.a the player of the game. The TV anime broadcasted from July 3 to September 25. Manga adaptation by Tsuyoshi Daichi has been released via Young Ace magazine since June 4.
Source: Official site