Urk, I had forgotten about this... Sorry.
Technically, Kanpachi's House is in Icytown, and Icytown is not in Cave Story. Grasstown is in Cave Story, however. Therefore, Kanpachi's House is correct.
Again, sorry for forgetting.
Question 16:
Who is the Optional Boss Fight inside the Prefab House in Shane's Cave Story?
[1 point]