Nagatophyllum satoi zone
About 40 m thick.
Rugose colonial corals extremely dominant. Additionally encrusting algae (solenoporaceans) and bryozoans.
Bryozoans forming individual reefs in Akago area.

Ref. 1897:
Strong horizontal zonation:
Lower reef front (frame-bindstone)
Upper reef front (framestone)
reef crest (frame- bindstone)
outer reef flat (frame- bafflestone)
inner reef flat (bindstone)
back reef slope (frame- bindstone)

Examples of coral genera in reef core:
Petalaxis
Ozakiphyllum
Pseudopavona
Ivanovia
Siphonodendron
Echigophyllum
Hiroshimaphyllum
Amygdalophylloides
Geyerophyllid gen. nov.
Taisyakuphyllum
Dibunophyllum