where to buy lobster

hello everyone,

my birthday is coming up soon and I would like to host some of my good friends to throw a lobster party at home. back in America, I would just go to a seafood store (or costco) to get some lobster and just boil at home but not sure where I can find decent quality lobster in Tokyo.

I've been to few seafood store but no good. havent visited costco yet but would that be the only option? thank you!