Trinity Seven has had a considerable amount of success with its Season 1, and it soon managed to gather a huge number of fans. Even though the popularity of the series implied that the producers would release the next sequel quickly, there are still no official announcements regarding the matter.
The storyline of “Trinity Seven” follows a High School teenager, Arata Kasuga, who comes to the conclusion that he has been living in an illusionary world, previously demolished and obliterated after a Breakdown Phenomenon. This phenomenon also affected his own life, as his friend and cousin Hijiri Kasuga was transferred to a different dimension. His mission soon becomes finding his sister, as well as saving the world.
For that reason, Arata Kasuga goes to Royal Biblia Academy, and there he links up with “Trinity Seven” i.e. Lilith Asami, Arin Kannazuki, Levi Kazama, Mira Yamana, Akio Fudo, Yuti Kurata and Lieselotte Sherlock..
The reason for still not having Season 2 of the series is the shortfall of the material and most likely scarcity of ideas. Namely, what happened is that the Season 1 covered all 30 chapters of the manga. Now, when it comes to Season 2, not only does it have to find the additional material for the series but it also needs to catch up the previous season, and have at least as many episodes.
This probably means that some more time will pass before the sequel comes out. Exact release date is not known yet, but speculations suggest that it might not happen during this year.