Nidan-jikomi (Two-stage preparation)
Japanese: 二段仕込み（にだんじこみ）
Adding koji in two stages to increase flavor complexity.
Nidan-jikomi adds koji in two stages. First portion is mixed in initially; after fermentation progresses, the remainder is added.
Staged addition layers flavors from different fermentation stages, creating complexity. More labor-intensive than single-stage, but worth considering for depth. The same staged approach applies to sake brewing. The first stage's umami is layered with new enzymatic breakdown from the second addition. This creates multi-layered depth impossible with single-stage preparation. Varying the time gap changes flavor.