the green fruit is at its best for juice from August to September The fruit is supple to the touch. The excellent book « Illustrated tips for growing and pruning domestic fruit trees » (図解だからわかりやすい家庭果樹の育て方＆剪定のコツ) Shufunotomosha, 2017 ISBN 4074240076, 9784074240074
advises to put green fruit in closed plastic bags with a moisture absorbent and to store them at a temperature of 3°-4°C.
Kurashiru advises against keeping the Sudachi at room temperature (loss of flavor), he puts them in a bag after having wiped them well and puts them at the bottom of the vegetable drawer (7°- 8°). He divides the Sudachi into several plastic bags to prevent a damaged fruit from spoiling the others.
The site sudachi.net is the most explicit with easy to understand photos; they make small bags of just 3 fruit each. https://sudachi.net/recipe/keepflesh
According to Japanese sources, green fruit can be kept for up to 20 days (frozen fruit for up to 8 months). https://cojicaji.jp/cooking/preservation-method/3027
