What is "kokai"

A kokai or kokai tokkyo koho is a published, unexamined Japanese patent application, in contrast to the kokoku or tokkyo koho, the examined and approved Japanese patent application. Kokai means "open to the public", or "laid-open". Kokai are published eighteen months after the earliest priority date.

Tokukai is another shorthand for "kokai tokkyo koho". Tokkyo (patent) + kokai (open to the public) = tokukai.