Necessary
Shaving the hair off a geoduck before you try to eat it is absolutely necessary. If you don't, the hair will get caught in your throat and you'll choke. It is necessary that you remove the hair.
Picture the page in your cookbook where it says "Shaving the hair off your geoduck = Necessary!!" It's absolutely necessary that you follow that instruction!
す, しゅ
すべから, すべし, ひげ, まつ, もち, もと
None
It is also necessary that you wear a suit (す) when eating shaved geoduck. It's a super fancy meal so a suit is necessary for you to enjoy it correctly.
What's necessary? To shave the hair off your geoduck and to wear a suit. That's not too hard. You should do it.