Tenchi Muyo! Ryo Ohki is the title of the original 1992 OVA series that started a long-running cross-media franchise, with numerous sequels and spinoffs. The original OVA received the Tenchi Muyo! Omatsuri Zenjitsu no Yoru! (Tenchi Muyo! The Night Before The Carnival), Tenchi Muyo! Ryo Ohki Dai-2-Ki (Second Season), and Tenchi Muyo! Ryo Ohki Dai-3-Ki (Third Season) sequels. Most recently, Tenchi Muyo! Ryo Ohki Dai-4-Ki (Fourth Season), the fourth OAV, debuted in 2017 as the first entry in the OVA series in 11 years since last episode of the third OAV debuted in 2005.
Source: Comic Natalie