I thought he was saying Hocotate in his own unique Japanese accent.
Is it really a new planet or just a mishearing?
Hocotate and Koppai would have distinct pronunciations in Japanese, even the English spelling of Hocotate might be confusing English speakers into thinking it's pronounced "Ho-ko-taet" instead of "Ho-ko-tah-tay", which is correct.
Koppai is a different word with a different pronunciation. Japanese is a much simpler language than English in terms of pronunciation.