I read it some time ago, and I can't remember the name, maybe someone here knows. It's a story about a guy who has a weak heart, and has to leave school for a while an go to the hospital. In the hospital he meets a girl, she's bit weird, I think she had some mental disease. She lives there and I remember he finds her for the first time in a refrigerator, she was sleeping. They become friends an all. I also remember that at the end she turns out to be his real mother, and i'm not completely sure about this, but I think she gives the boy her heart... yeah I suck at this, sorry. but maybe someone has read it, or something that's similar, or knows the name of the mangaka? heh, sorry for taking your time & thanks for reading! Also! i apologize for my bad english.

Nanairo Sekai

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"Officially, this machine doesn't exist, you didn't get it from me,
and I don't know you. Make sure it doesn't leave the building."

yey! Is that one exactly! thank you so much!