Layout of each Floor of the Underworld

Each Strata or the Floor of the Underworld is comprised of 2 sections: 1) The Netherscape which contains various enemies and 4 Jizo-Kodama; 2) The Crucible which contains the main boss of the Floor. Once spawned into the Netherscape the player can collect anywhere between 1 and 4 Jizo-Kodama. The player must collect at least 1 Jizo Kodama in order to move onto the Crucible. Once the player has collected at least 1 Jizo-Kodama a portal will appear at the location of where the player collected the Jizo-Kodama as well as a portal next to the Shrine. Once the player is in the Crucible they cannot return back to the Netherscape. In order to go the next Floor of the Underworld the player must defeat the Boss in the Crucible. Below contains the full list of all of the Bosses on each Floor.

Farming for specific Graces in the Underworld

If Floor Number / 3 = 0.333 : Acala's Grace, Ame-no-Uzume's Grace, Grace of Kagutsuchi, Izanagi's Grace, Omoikane's Grace, Takeminakata's Grace
Floors that this Grace pool appears on: 1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31, 34, 37, 40, 43, 46, 49, 52, 55, 58, 61, 64, 67, 70, 73, 76, 79, 82, 85, 88, 91, 94, 97, 100, 103, 106

If Floor Number / 3 = .666 : Grace of Amaterasu, Grace of Owatatsumi, Izanami's Grace, Magatsuhi's Grace, Marici's Grace, Ninigi's Grace
Floors that this Grace pool appears on: 2, 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 35, 38, 41, 44, 47, 50, 53, 56, 59, 62, 65, 68, 71, 74, 77, 80, 83, 86, 89, 92, 95, 98, 101, 104, 107

If Floor Number / 3 = .000 : Grace of Futsunushi, Grace of Susano, Grace of Takemikazuchi, Grace of Tsukuyomi, Okoninushi's Grace, Sarutahiko's Grace
Floors that this Grace pool appears on: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96, 99, 102, 105, 108

Underworld Floor Crucible Boss List