Japanese love molluscs; squid, cuttlefish and octopus. However Japanese do not eat these types of molluscs as same ways. Squid and cuttlefish are very common to eat as tempura, but octopus tempura is uncommon. Also deep fried squid and cuttlefish with breadcrumbs are also very popular but deep fried octopus with breadcrumbs is not.
On the other hand, takoyaki, octopus ball is very popular but squid or cuttlefish ball version does not exist. Octopus is also used in Japanese style salad with sweeten vinegar but squid and cuttlefish are not used in salad.
However, these molluscs are eaten as sashimi in Japan. Especially sashimi of squid is popular and could be eaten nationwide. Of course the squid must be fresh.