"A type of demon whose body is covered in tangled black fur. Alps appear in Norse mythology and come in two varieties: the light Ljósálfr and the dark dökkálfar. The word Alps normally refers to the former. In Alfheim, the paradise in which the elves of the sky live, they dance and bathe in the light of the moon. When Christianity came to Scandinavia, the alps were branded a race of demons and have remained so ever since."
—Shin Megami Tensei IMAGINE Compendium
Alp appears in Suginami and Ichigaya at night and within Shinjuku Babel's docks. A stronger variant can be encountered in Nakano's gold level Stone Site instance and in Suginami's Diaspora instance.
Devil Summoner: Raidou Kuzunoha vs the Soulless Army
"A dream demon of German lore. They can transform into various animals and cause night terrors. Like other demons, they feed on blood, but will also milk from sleeping women."
—Shin Megami Tensei: Devil Summoner: Raidou Kuzunoha vs the Soulless Army Devil Chart
Persona 3 FES/Portable
"A succubus of German and Swiss folklore. Originated as beings which forged mystical crafts under the mountains, they later came to be seen as demons that prevented people from sleeping, causing illness."
—Persona 3 FES Compendium
Alp can be obtained via fusion, or by rare chance, through Shuffle Time in the first block of Tartarus, Thebel.