This is one of the AV Open 2017 Entries in the Mania category. The main focus seems to be the announcement of the retirement for Sora Shiina and Nanako Tsukishima (aka Eririka Katagiri), who are known to be each others' girlfriends.
The studio pulls in 7 other JAV actresses to join in on the festivities. They have various 'contests' with pairs of actresses competing at an activity, following which the winner will have the star pair Sora and Nananko do the same activity to them. The actresses french kiss, fuck themselves with vibrators and dildos, use a double ended dildo to fuck each other, finger and eat each other out, and lick each other all over, with each winner getting their reward. This is followed up with a lesbian orgy with everyone fucking everyone else. There is also a 3P scene where Sora and Nanako fuck one of the other actresses, and then a final scene where they spend a long time fucking each others' brains out with a lot of frenching, fingering, pussy rubbing and emotional crying. It ends with the usual 'graduation' or retirement scene where the pair are given flowers and make small speeches to commemorate their career.