I'd resurrect the other thread, but I might get in trouble if I decide to do that every 12 months. Besides, it seems kind of silly in retrospect when we already have this one, so here goes.
The best 10 songs I found that came out in 2021:
1. In Hell We Live, Lament - Mili
2. Hadashi no Step - LiSA
3. One Last Kiss - Utada Hikaru
4. Manners - Band-Maid
5. Bulbel - Mili
6. "M" Revolution - Unlucky Morpheus
7. Surprise - LiSA
8. Fiction - Polkadot Stingray
9. Darken - Zutomayo
10. Messenger in Flames - Cepheid
The best 10 songs I found in 2021 but that came out before:
1. Dokuhaku - Maaya Sakamoto
2. sustain++; - Mili (technically listened to this one last year, but it kind of fell into oblivion after the first time. This year I became obsessed with it)
3. Haru wa Yuku - Aimer
4. Summoning 101 - Mili (the fastest I've gone from 0 to a tear shower (just under 3 minutes))
5. FATE - Band-Maid (all of World Domination really)
6. Komm Susser Todd - Arianne (same as sustain++; but all the way back in 2015)
7. Odore Ophelia - Feuille Morte/RD-Sounds (one of those names is the artist name. Couldn't figure out which. This song is obscure, it's not even on youtube anymore)
8. world.search(you); - Mili
9. Standstill - Poets of the Fall
10. Dear Alice - Arai Tasuku
And the best 10 background themes from a soundtrack, which all happen to be from video games:
1. Spiral of Erebos - The Legend of Heroes: Trails of Cold Steel III
2. Dark Beast Ganon Battle (spoilers for final boss I guess) - The Legend of Zelda: Breath of the Wild
3. Great Power - The Legend of Heroes: Trails of Cold Steel
4. Make Me Feel Sad - Dragon Quest V
5. Harmonious - Ender Lilies: Quietus of the Knights (composed by Mili)
6. Triumphant Return - Epilogue - Dragon Quest VII
7. Pledge of Demon - Yakuza 0
8. Twilight Green Passage - The Legend of Heroes Trails of Cold Steel IV
9. Bewitching Dance - Monster Hunter Generations Ultimate
10. Severe Blow - The Legend of Heroes: Trails of Cold Steel II
Special mention here to Morimiya is Okay from Tokyo Xanadu. It was my number 10 but I wanted a CS2 theme just to round things up so it had to be sacrificed.
This is also the year when I just had to accept that Mili is my current favorite band. It was evident before but the more I listen to, the more obvious it becomes. I really recommend it, they make some weird stuff in terms of the lyrics actually fitting into a melody sometimes, but it's great. They go from crude reality to sci-fi to fantasy to a mix of all three like it's nothing. You could make a compilation of their lyrics and sell it as a short story collection.
It's also probably worth mentioning Vivid Undress as probably best discovery of a band? Spotify does a weird thing where if a playlist/album is over it just goes on playing whatever it thinks I might like. The thing was right, I listened to a few of their songs and they're storming great. Parareru wa (or something) particularly stayed with me. I love discovering bands like this, it's like an adventure. It happened almost at the end of the year so I'm excited to listen to all of their stuff.
I'll also be checking out Band-Maid's early stuff because I feel like I abused too much of World Domination this year.