 If you liked
Yousei-san wa Yaritai Houdai
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 ...then you might like
Kimi to Oishii Ai no Kotonoha
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a student rescues small supernatural creature off the streets. the little guy then turns into a very human-sized guy, and attraction sparks between them. but apart from attraction, he also has to feed off energies the mc produces (like sweet words or the feeling of happiness). ending twist is also similar.