rice cake wrapped in an oak leaf
A traditional Japanese sweet made of mochi filled with sweet bean paste and wrapped in a pickled oak leaf, eaten especially on Children's Day.
There is a custom of eating kashiwa-mochi on Children's Day.
sleeping curled up in a futon
Colloquial expression likening a person sleeping with a futon folded over them to a rice cake wrapped in an oak leaf.
On cold nights, I sleep wrapped up in my futon like a kashiwa-mochi.