S1·E15 Neptune is Beyond My Closet

First appearance of Oyuki, Lum friend and queen of Neptune. Oyuki also has incredible ice powers. Megane and friends visit while Shinobu is nursing Ataru, who has a cold; and they discover a gate to Neptune in Ataru closet. By accident, they go through this gate and arrive on Neptune to be greeted by Lum and Oyuki.