Please help! I once read a manga before regarding demons lending their hearts to humans to...

Sounds intriguing -I would be interested to read as well.

If someone does know, please pass it on.

I found it after searching the demon tag! If you want here it is.

http://www.mangago.me/read-manga/hanatsukihime/

Thank you, Thank you- I just saw this before leaving for work! Will check out during break!

(=・ω・=)