Urusei Yatsura: Lum the Forever is the 4th movie released as part of the 1981 Animated Adaptation of Urusei Yatsura. Like most of the films, it is a Non-Serial Movie featuring a storyline completely unique to the anime. It aired between episodes 191 and 192, making it the last of the movies to be released during the run of the 1981 anime.
As part of a student amateur film production, Mendo permits the students from Tomobiki High's Class 2-4 to cut down a giant sakura tree called Tarōzakura that has been growing on the Mendo estate for 300 years, due to the tree being heavily rotted at its core. After it has been chopped down, however, things start to get extremely weird, centering around the disappearance of Lum.
The fourth film is the subject of much debate, as it is probably the hardest of all the Urusei Yatsura films to fully understand. Many consider it to be a multi-layered masterpiece, while others feel it is little more than a confused and rambling mess.
This movie contains examples of:
- Aw, Look! They Really Do Love Each Other: Ataru genuinely misses Lum once he understands that she has been taken by Tarōzakura, and is palpably relieved when she is set free. Though it takes a shove from Kotatsu-Neko for him to get going, he ends the film by running into Lum's arms and embracing her, outrunning the Stormtroopers' attempts to shoot him down in the process.
- Botanical Abomination: Tarōzakura is an ancient sakura the size of a giant sequoia. Centuries-old, it has tremendous spiritual presence, and is deeply respected by the local youkai population of Tomobiki, who come to engage in a night-time hanaminote out of respect for the dying tree. When Ataru strikes what was expected to be a ceremonial blow with a salted axe, fetid green slime spews from the wound, which rapidly spreads through the tree's trunk until it is completely severed and it crashes to the earth, whereupon it dissolves into a puddle of noxious goo. But its spirit remains actively present as a Genius Loci, first creating bizarre swarms of animals that attack the students of Tomobiki High, then reshaping the mountain on which it stood into an unnatural lake and finally trapping the entire city and all its denizens in a dream world. Things only return to normal when the spirit of Tarōzakura decides to let Lum and everybody else go.
- Brought Down to Normal: Once Tarōzakura begins focusing its attention on Lum, it starts feeding on her strength, which rapidly drains her powers; her electro-shock ceases to hurt, and she becomes slower and slower at flying.
- Friendly Enemies: When the Mendo and Mizunokoji families go to war, they draft all of their employees to supplement their private armies, but the drafted civilians remain perfectly friendly with each other despite fighting. Ataru's father is shown exchanging pleasantries with a neighbor who'll be fighting on the other side of the war as they get ready for that day's battle, as if it were just another day at the office.
- Genius Loci: Tarōzakura's spirit is intimately intertwined with the entirety of Tomobiki. It can manipulate the ground and the local animals, and watch people through ambient video cameras. When Lum briefly communicates with it, the being describes itself as "still no more than the memories of this town".
- Genre Mashup: The students' movie begins with an obvious homage to 80s Slasher Movies, but then turns into an adaptation of a Japanese folk story (said in-film to be a family legend of the Mendos).
- Human Sacrifice:
- When the remains of Tarōzakura are unearthed from the bottom of the spirit-fashioned lake, the remains of an ancient human sacrifice are discovered tangled in its roots.
- Towards the end of the movie, Shutaro Mendo tries to have Tobimaro Mizunokoji killed, apparently to enact another such sacrifice to quiet the sakura's restless spirit.
- Nice Job Breaking It, Hero: In the in-universe movie, the protagonist cures the sickly village elder by chopping down the giant sakura tree standing over the village, which is was causing his illness by feeding on his strength. However, the sakura tree was also guarding the village from evil spirits, so with its death, they began to run rampant in the village. It was only a beautiful oni princess descending from the heavens and banishing them with holy light that saved the villagers.
- O.O.C. Is Serious Business: One of the earliest signs that Tarōzakura is attempting to manipulate the minds of Tomobiki's residents is when each member of Lum's Stormtroopers finds themselves suddenly crushing on a different girl. As they point out when the spell breaks, they've never been interested in girls before.note
- Related in the Adaptation: It's mentioned briefly by Shutaro that his research has revealed the Mendo and Mizunokoji families are distantly related, so Tobimaro and Shutaro are actually remote cousins.
- Ship Tease: The first sign that Tarōzakura is trying to wipe Lum's presence from Tomobiki's memories is when Mendo asks Shinobu on a date, which is something she's wanted for the entire seriesnote ... And then Mendo remembers Lum just as he is about to give Shinobu a goodnight kiss, causing him to run away from her to chase Lum, whilst an angry Shinobu rips a bus stop sign out of the sidewalk and twists it into a knot in frustration.
- Sole Survivor: In the in-universe movie, Ataru plays the role of the sole teen to get away from the mutant/undead killers who attack a bunch of campers at a cabin in the woods.
- Speaks Fluent Animal: It's noted at the beginning of the movie's second quarter that Ran and Lum used to be able to communicate with animals via an empathic link, although this ability has waned steadily as they aged and will soon vanish entirely.
- Un-person: As the spirit of Tarōzakura begins trying to claim Lum for itself, it attempts to wipe her from the memories of everyone in Tomobiki. This leads to a notable sequence where Lum runs into Shinobu and Mendo on a date and greets them, happy to see them finally hooking up, only for them to stare back at her as if she was a complete stranger. The Stormtroopers all find themselves temporarily smitten with other girls from Tomobiki as well. However, the sakura spirit fails in this plan, as Mendo and the Stormtroopers all spontaneously regain their memories, and Ataru's never waver.
- Well-Intentioned Extremist: Shutaro attempts to free Tomobiki from the strange dream-world that Tarōzakura traps them in first by making a Human Sacrifice out of Tobimaro Mizunokoji, and then by fighting a war with the Mizunokojis. One fan theory is that Shutaro's plan was that by fighting this war, he would unite the denizens of Tomobiki in dreaming of the real world, which would break Tarōzakura's powers and send them back to reality.
