Nakai-san (中井さん) is a small reindeer that belongs to Shiwasu Kakeru.
He has a big red nose and a brown necklace with a yellow bell as the medal. He is smaller than Kakeru's shoulder.
- Nakai-san is a symbol of Christmas.
- He lives in the dorm with Kakeru even when Christmas ends.
- He often leaves gifts for Kakeru, such as pounded fishcake. 
- Nakai-san's name may come from tonakai (トナカイ), which is the Japanese word for "reindeer".