According to Wikipedia, mochi is a
Japanese rice cake made of mochigome, a short-grain japonica glutinous rice. The rice is pounded into paste and molded into the desired shape. In Japan it is traditionally made in a ceremony called mochitsuki. While also eaten year-round, mochi is a traditional food for the Japanese New Year and is commonly sold and eaten during that time.
Mochi is apparently also occasionally deadly. According to an International Business Times report, during the 2015 New Year celebration, 9 people died in Japan from suffocating on the snack, and 18 people were hospitalized in Tokyo alone.
The sticky, glutinous dish can get stuck in the throats of those eating it–especially those who are very young or very old–causing people to suffocate.