In Japanese mythology, Susanoo, the powerful storm of Summer, is the brother of Amaterasu, the goddess of the sun, and of Tsukuyomi, the god of the moon. All three were spawned from Izanagi, when he washed his face clean of the pollutants of Yomi, the underworld. Amaterasu was born when Izanagi washed out his left eye, Tsukuyomi was born from the washing of the right eye, and Susanoo from the washing of the nose.
In Megami Tensei II, after the Partner gets kidnapped by Astaroth and before the hero rescues her, he can search around the Lost Woods to find a trail of food and scraps. Following it leads him to a girl, who reveals herself to be Susano-o. Upon returning to his form as a deity, he joins the hero.
Shin Megami Tensei IMAGINE
Susano-o appears regularly as both a mini-boss and final boss in two of the boss rooms for Ichigaya's Kagurazaka Zhu Que Cavern's gold-level instance. His plug-in item can be acquired from the end chest in his boss room as a rare reward. He can be fused in a special triple-fusion of a Yatagarasu variant, Kushinada-Hime, and Okuninushi.
Shin Megami Tensei IV
"A violent god of Japanese legend. He was one of three gods born from Izanagi.<br\>Originally banned from Takaamagahara for uncouth behavior, he later performed heroic deeds such as slaying Orochi and became a great god of Ne-no-Kuni"
—Shin Megami Tensei IV Compendium
Shin Megami Tensei: Devil Summoner
One of the cases Mary Kisaragi gives to the protagonist is to go the Hikawa shrine and investigate the recent hauntings surrounding the area. When he reaches the shrine, he comes across a man who transforms himself into his true form, Susano-o. He warns the protagonist that 'the seal is getting weaker'. He then fades away, and the area returns to normal.
Devil Summoner: Soul Hackers
"A violent god of Japanese legend, he was one of three gods born from Izanagi. Originally banned from Takaamagahara for uncouth behavior, he later became a hero by defeating Yamata-no-Orochi, and eventually became a great god of Ne-no-kuni."
—Devil Summoner: Soul Hackers 3DS Compendium
Devil Summoner: Raidou Kuzunoha Vs The Soulless Army
Susa-no-O challenges Raidou Kuzunoha the XIV in Dark Ginza-Cho. He holds the Fire Prism, one of the four components of Amatsu Kanagi.
"A god of Japanese legend, born along with Amaterasu and Tsukuyomi. He was cast out for lewd behavior, but redeemed himself with heroic deeds like slaying Yamata-no-Orochi."
—Persona 3 Compendium
Susa-no-O appears as the ultimate Persona of the Fool Arcana. He can only be fused after completing the S.E.E.S. Social Link, reaching level 76 and can only be obtained by fusing Orpheus, Legion, Ose, Black Frost, Decarabia and Loki in a Hexagon Spread in the Velvet Room.
Persona 4
Susano-O serves as the ultimate Persona of Yosuke Hanamura. However, his appearance is very different to his original one, probably as a result of sharing a similar model to Jiraiya. Instead of a disco uniform, it is replaced with a blue long-sleeved jumpsuit with a yellow belt, red gloves, and red boots. His head is more shiny and the ears, shurikens on his face, and other details are gone, and replaced by a pair of yellow glasses or goggles with blue lenses. He also has a spinning ring around his body that looks like a sawblade with only the blade part.
DemiKids Light & Dark
"Exiled from the skies, this demon of the seas now rules over wind and thunder."
Susano-O appears during Amane's 8th day route. He presents himself to Honda, who is trying to escape the lockdown with a COMP. Upon defeating him during battle, he can be fused.
Devil Survivor 2
"A violent god of Japanese legend, he was one of three gods born from Izanagi. Originally banned from Takamagahara for uncouth behavior, he later performed heroic deeds such as slaying Yamata-no-Orochi and became a great god of Ne-no-Kuni."
—Devil Survivor 2 Compendium
Susano-o is unlocked by reaching Fate rank 5 with Keita Wakui.