The Kuramoto family consists of three generations: Eri, her married son and his wife, and their grandson Kameji. The married couple works full-time and is always busy, so Kameji has been raised by his grandmother Eri since he was young. One day, they decided to go on a hot spring trip to celebrate Eri's 60th birthday, but along the way, the couple's situation seemed suspicious as usual due to their busyness, leading Eri and her grandson to head to the inn alone. The two who arrived at the hot spring…
