“mutual mastu” is pure elegance: a graceful Asian woman in a kimono that falls open like petals. Delicate fingers part soft folds in “mutual mastu”, showing how wet silk has made her. The gentle rhythm she sets in “mutual mastu” gradually becomes urgent—small breathy cries turning to desperate whimpers. When the final wave crashes in “mutual mastu”, her composure shatters beautifully, leaving only trembling satisfaction.