Takayan is an artist who does hip hop and rap and his lyrics tend to be about issues like mental health, bullying, relationships and so on. He does seem to dabble in other styles but I'm not great at pinpointing genres on my own so all I can say is that his songs are can be aggressive (i.e. Desperately want a lover, Date me! Not them), melancholic (i.e. Toy, Curse) or relatively cheerful/hopeful (i.e. Bad Example, What's the Meaning of Living). I honestly find his songs very comforting and he seems to care about his fans a lot, considering he's even written songs about them like Listeners are World Heritages!
And then there's also Hypnosis Mic as a whole. There's actually a lot of lore behind it but I think anyone can enjoy the songs without learning the context behind it all. Long story short, it's just a bunch of anime men rapping against each other. My favourite song at the moment is Black Journey by Fling Posse (aka one of the fictional teams within this franchise.) but that's subject to change. I'm honestly looking forward to hopefully getting another song by the only female group Party of Words since I absolutely loved the vocals of the seiyuus in FEMME FATALE.
And there's also SID! I don't know too many of their songs just yet but I know their songs from Fullmetal Alchemist Brotherhood. That series was part of my childhood growing up so the songs Uso and Rain really stuck with me. In all honesty, if you haven't, I really recommend looking into the artists behind the openings and endings of the FMA franchise. I've already seen L'Arc~en~Ciel recommended here though so that's pretty pog!
And apologies for rambling so much. I'd even go into various VOCALOID producers but I think I've spoken enough for now haha
