Rainy Brother 1 appears on B1F and B2F of the Secret Laboratory within the Midnight Channel on rainy days. When defeated, it may drop 1st Boy's Talc. Selling 1st Boy's Talc at Daidara Metalworks will unlock the Bloody Kunai for Yosuke Hanamura in the shop, which has the second highest attack rating of weapons available from the Secret Laboratory, and also boosts the damage of his Wind spells by 25%.
In Golden, Rainy Brother 1 appears on B1, B2, B5 and B6. It may also drop Meteorite, Rose Quartz or Buffalo Stone for trade at Shiroku Pub. Selling four 1st Boy's Talcs will unlock the Bloody Kunai for sale.
Persona Q: Shadow of the Labyrinth
Rainy Brother 1 appears in Story 4 of the Evil Spirit Club. It attacks with single-_target, elemental Physical skills and may decrease the party's hit and evasion with Masukunda. When defeated, it may drop Elder Piece, Elder Mist, and Elder Core. Elder Piece is used to create the Pugilist's Fists for Akihiko. Elder Mist is used to create the Kaneshige for the P3 hero. Elder Core, only obtainable by killing Rainy Brother 1 with Electricity, is used to create the Paralysis Robe for Zen and Rei.