Japanese MMO Rankings not so popular as Korean MMO Rankings but at least we can see number of votes and 'emotions' with comments below each game.
Japanese MMORPG Ranking
For Japanese Online Games Rankings I use mmo info

Top 10 Popular MMORPG in Japan (August)
1. Tree of Savior (Japanese server)
2. Dragon Quest X
3. The Elder Scrolls Online
4. Seventh Dark (Laplace, X-Legend Entertainment MMO)
5. Black Desert
6. Mobile Suit Gundam Online
7. FINAL FANTASY XIV
8. Terra
9. Phantasy Star Online 2
10. Cabal Online

Famous MMO in Top 100
13. Bless
18. Soul Worker
19. War Thunder
26. Ragnarok Online