As always, opinions are mine, not those of Lichess.org.
Perhaps some J-pop expert may set me in my place, but I believe virtual idols are exploring a new subgenre, characterized by:
Lyrics uncompromisingly feature a story, even when this requires compromise on language, ease of singing, or vowel quality
Upbeat tempo, with smooth changes in metric modulation (e.g., alternation between cut time and common time)
Powerful rhythmic vocals with frequent melodic leaps and complex rhythms; drums alternate between powerful sections and relenting to let lyrical vocals and other rhythm instruments to take center stage
I make this claim in the hope of hearing more songs in such a subgenre; in the West we've heard thousands of popular songs with simple melodies and intense drums, and while countless people appreciate popular music, I struggle to find it moving. Great songs should tell a story and tell it well.
Honestly, I couldn't in my wildest dreams imagine finding popular modern music as fascinating as the western classical tradition. And yet composers like David Lanz and Joe Hisaishi give me pause... can modern music convey a story?
Hololive songs which support my claim (again, I am stunned to enjoy anything popular):
Hakos Baelz - Mind Craft (cover)
Sometimes, piano, voice, or rhythm guitar are the only percussion instruments.
Hoshimachi Suisei - Bibbidiba (honorable mention: Stellar Stellar)
The drum part is quite clever, and equally clever is how it leaves space for vocals and other instruments to jazz in the foreground (incidentally, this increases the karaoke challenge difficulty - god bless Minato Aqua for her courageous attempt!).
Mori Calliope ft. Kobo Kanaeru - Midnight Mayoi
Synthesizer and rhythm vocals can clearly be heard; drums play a mostly predictable loop, and take several rests.
IRyS - Carbonated Love (honorable mention: Gravity)
Sure, this is Eurobeat, but melodies, rhythms, and lyrics are complex, and incredibly there are multiple sections without bass and without drums.
Image credit: Marius Masalar