Candy
What do you eat like a machine? Candy!
None
あめ
None
This candy in particular is just drops of hardened, clear sugar that looks like 雨 (あめ) drops.
An update is needed before you can continue but you have more than one WaniKani tab open.
Finish up what ever you are doing on the other tab(s), then close them to continue.
The update will complete automatically once the other tab(s) are closed.