Moh Shuvuu means "Evil Bird" in Buryatian, she is the spirit of a young girl who died before knowing love. Moh Shuvuu takes on the form of a beautiful woman and lures men to an isolated spot. She then reverts to her true form of a bird and attacks.
Moh Shuvuu appears in the Nakano Boundless Domain instance and is notable for being the only demon to learn Vinyl Strike, a suicide skill with an extremely high damage modifier. She is the main NPC in the 2014 Valentine's Day event where she takes players to a special Valentine-themed version of Shibuya's Quartz instance.
"Meaning "evil bird," it's the ghost of a young girl who died without knowing love in Buryat lore. She seduces travelers, only to crack their heads open and suck out their brains with her beak."
—Shin Megami Tensei IV Apocalypse compendium
Moh Shuvuu is a resident of the Fairy Forest and may be found throughout its initial southern areas. She can teach the Dia, Zan, Makakaja and Mazan skills during Demon Whisper. Moh Shuvuu receives a decent bonus to Force skills and a small bonus to ailment and healing skills inherited through fusion.
Moh Shuvuu is first seen at the Amami Airport. They are fairly dangerous due to their ability to use Last Resort, which could easily devastate the party if they opt to self-destruct.
In the 3DS remake, a variant Moh Shuvuu is available from Nemechi, after it evolves into the snake form. She costs 100 D-Souls and uses her alternate palette swap from the first Devil Summoner installment. This version is stronger and can use Loyal Electricity to rain lightning on opponents.
Furthermore, a Moh Shuvuu appears on the team of Raidou Kuzunoha the XIV if you challenge him in his optional boss fight. This Moh Shuvuu is much stronger than all other incarnations of the demon, being level 80 with matching stats and thousands of HP, a huge list of resistances, no weaknesses and several near-unique skills.
Although she is, of course, completely optional as a demon in the games in which he stars, a Moh Shuvuu seems to be a core component of Raidou Kuzunoha's "canon" demon team; in every single appearance Raidou has made outside of his own games where he summons demons (that is, Devil Summoner: Soul Hackers, The Lone Marebito & the "Chronicles" edition of Shin Megami Tensei III: Nocturne), she is present and a heavily-used summon.
This particular Moh Shuvuu is also often shown having powers that would be difficult, at best, for a playable one to have, such as Frolic or her Dekunda-esque ability in Nocturne. She also has "impressive" stats (to say the least) when targetable in Soul Hackers.
The only other demon to appear so consistently like this is Raidou's Mokoi.