This series were always a Doujin Production so my best answer is that there isn't enough funds to generate a second one and probably there isn't enough chance of making profit to justify it (as Yuri is still a minor genre, which is funny because yaoi is a major genre, lol). Secondly the director of that OVA is Saiko Masayuki...the guy who worked on FMA/Bro, Noragami, Re:Zero...so yeah he is kinda busy now...
Base +10, Star God +4, Ubersuntzu +34, Belloner +2