Mofu Onee-san no Atatame-kata

"I received this life to warm you up." Minato, a boy who is really sensitive to cold, meets a mysterious girl, Kokoro, on his 15th birthday in winter. Kokoro says that she's an artifact spirit that born to warm Minato's heart, and would do anything to make sure he is warm to the core! A very exciting manga with "Warming Action" and an older woman!!