If there’s such a thing as art-house improv, this is it. With their quasi-mystical “Japanese” aesthetic, minimalist pacing and blocking, and character-driven humor, the expert Promise Keepers mold the paradigmatic Harold to their sophisticated sensibilities. Adroitly accessing standard techniques when needed, the four improvisers introduce exciting moments, like a fistfight, but succinctly downplay them for dry comic effect. Conversely, ordinary events, such as a family sitting around talking, assume amusing dramatic potential. Lines spoken in character–“What’s that supposed to mean?” “Well, that was weird,” and “Why are you taking your pants off?”–apply equally to the show itself. What easily could’ve been boring and self-indulgent is kinky, justifiably methodical, and seductively offbeat. –Ryan Hubbard a Open run: Wed 10 PM, I.O., 3541 N. Clark, 773-880-0199, $5.