Sangatsu Boujitsu, Kuma wo Hirotta

One morning, Kyuya wakes up to find that he's bedded a bear. That bear is Hozumi, an older man with a scruffy beard and a penchant for clinging to Kyuya and calling him "Kyu-chan". Hozumi's desperate behavior is a big turn-off for Kyuya, however, Kyuya slowly learns that there is more to Hozumi's desperation than he could have imagined.

(Source: Blissful Sin)