The "visitor from another planet" story is doable, even for an indie filmmaker with no budget. All you need are aliens who have assumed human forms, but don't quite get the whole humanity thing. Two recent examples are Kiyoshi Kurosawa's 2017 films "Foreboding" and "Before We Vanish," in which aliens rob humans of their concepts of humanity (work, family, love), all without a single CG assist.
Still another is Keiko Tsuruoka's coming-of-age fantasy "Makuko," whose 11-year-old hero Satoshi (Hikaru Yamazaki) is befriended by a new transfer student. Taller than him by half a head and somehow exotic and intimidating, Kozue (the single-named Ninon) takes an intense interest in Satoshi, peering at him like an entomologist inspecting an unusual bug. Worse, she and her mother, a maid at the hot spring Satoshi's mother manages in a mountain village, take up residence right next to the poor kid. No escape.
At first frozen into immobility by Kozue's closeness and close attention — in her presence he thrusts his arms straight down like a doll without elbow joints — Satoshi gradually relaxes and opens up to her.
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