In the special edition of volume 3 of shoujo manga "Kobayashi ga Kawai Sugite Tsurai!!
", to be published on July 26th, an OVA was announced to be attached. The cast is as follows:
Kobayashi Mitsuru/Kobayashi Megumu: Fujimura Ayumi
Sanada Aoi: Ono Daisuke
Tokugawa Azusa: Asakura Azumi
Source: Shogakukan manga website
Kobayashi ga Kawai Sugite Tsurai!!