Jingai-san no Yome

Tomari Hinowa, a completely ordinary high school boy, is summoned by his homeroom teacher one day and informed that he's been selected to become the wife of a mysterious creature called Kanenogi. Despite their uncertainty, the new couple registers their marriage... and starts a surprisingly happy new life together?! And thus the sugary-sweet married life of the soft, fluffy Jingai-san and the ordinary high school boy begins!

(Source: Crunchyroll)