～増し
～まし · ～mashi · JLPT N1 · noun
addition
📈 増 (zō, to increase) + し: attached after a noun, it means that amount plus extra, like 1時間増し = one hour and more
Comes from the verb 増す (masu, to grow). Attach it after a noun or number to mean that amount plus extra, as in 値段増し (price increase) or 1時間増し (an hour and more).