I remember reading a BL manga, about a boy who is an alien and turns into this colorfull blob whenever he gets overwhelmed with emotions. I forgot the plot, but I know it was a cute BL!
https://www.mangago.me/read-manga/chirijiri_yuku_no_cookie_jar/
I think the manga you're talking about is "Chirijiri Yuku no".
I remember reading a BL manga, about a boy who is an alien and turns into this colorfull blob whenever he gets overwhelmed with emotions. I forgot the plot, but I know it was a cute BL!