Kerokero Chime

Although the plots of these two series are almost completely different, and Dr. Rin is darker and more complex, they have a similar "vibe," probably because they are both shoujo titles animated by the same studio and share some staff. 

Both the main boy characters are cursed and transform when they get wet! Comedy and romance (very obvious hints of it). Ramna 1/2 has less emphasis on finding the cure for the curse and is more slice of life, whereas Kero Kero is about the journey to find a cure. Both made in the 90s!  

the story its a bit different but both share that the main cast was brought into a new world, need to find different pieces of magic spell to dissolve the curse and return were belong. if u liked TWHE then u will laugh with KKC