Ep. 40: Lum, Ataru, Shinobu, and Mendo spend summer vacation by the sea
Aired on August 18, 1982

During their summer break, Lum, Ataru, Shinobu, and Mendo travel to the seaside. Their vacation takes a supernatural turn when they inadvertently anger a watermelon deity. Following this incident, the group encounters a youkai that is weeping. These events mark the key occurrences of their time away from home.
Episodes
- Ep. 36 · Rei Returns and Causes Chaos in the Study Hall
- Ep. 37 · The Phantom Red Mantle Appears at Tomobiki High School's Summer Disco
- Ep. 38 · Lum attempts to create copies of Ataru to shield him from Ran's wrath
- Ep. 39 · Lum and Ataru go on their first date after Lum realizes their relationship is abnormal.
- Ep. 40 · Lum, Ataru, Shinobu, and Mendo spend summer vacation by the sea
- Ep. 41 · Typhoon Floods Tomobiki as Lum Helps Moroboshi Family Cope
- Ep. 42 · Lum and Ten become intoxicated by umeboshi and cause chaos
- Ep. 43 · Ataru, Lum, and Ten encounter a cat-like humanoid during the feline mating season.
- Ep. 44 · Ataru regrets yelling at Lum after she leaves to renew her passport