noun
kotatsu snail; person who stays under a kotatsu all winter
Colloquial, humorous term blending こたつ (kotatsu) and かたつむり (snail). Used to describe someone who curls up under a kotatsu and rarely comes out during winter.
See also: こたつ
冬になると、彼は完全にこたつむりになってしまう。
When winter comes, he turns into a total kotatsu snail.
休みの日は一日
On my day off, I stayed curled up under the kotatsu all day like a snail.