I Howl at The Moon
Lum makes some sakuramochi for Ataru to enjoy flower-viewing together. However, she mistakenly made something that is not suitable for human consumption and turns Ataru as well as Onsen-Mark into wolfmen, thus she must quickly prepare an antidote and force an elusive Ataru to take it or he’ll remain a wolf forever.
Aired 01/09/1989EP 7 - I Howl at The Moon

Urusei Yatsura - OVA Series
The adventures of Lum, Ataru, Ten, and all the gang from Tomobiki continue in an assortment of new – but no less weird – stories.
Watch as Lum, Ataru, and Shinobu encounter a rabbit-clad youth, enter the Room of Destiny, and get a glimpse into their futures in "Inaba the Dreammaker," or see Ran's plans to use a sherbet cone-producing bird to open a sherbet shop one hot Tokyo summer go terribly awry in “Raging Sherbet.” Ataru has yet another bad experience with Lum's cooking in "I Howl at the Moon".
(Source: Anime News Network)