help me remember this anime where a guy transforms into a demon??

i watched this show during the pandemic lockdown so maybe it was released then. i vaguely remember the guy i think got bestowed with a power to turn into a curse or a demon? and there was a blonde female character with a huge weapon (sword or gun) and i think she had a lion or a tiger. i think she also had a hat. probably had a B in her name. help did i hallucinate this?

much appreciation