It is not a stretch to recognize the similarities between hip-hop dance and Japanese butoh. As Rennie Harris said after the local premiere of Flash on Friday at the Painted Bride, both are forms of crisis and contradiction and grew from mid-20th-century historical and social contexts. Each seeks a new aesthetic.

Master practitioners Harris and Michael Sakamoto have been exploring their genres for years - the moves and motives of what they do as a way to reflect on who they are now. They achieve some insights into themselves, how they relate to each other, and how their art forms engage with, mirror, and change each other - and maybe us.

They explore their psyches through recorded interior monologues, dialogues, the languages of their inventive movement, even lullabies. It begins as a pseudo-battle of wills and wits, when Harris, who, at 50, no longer does head spins, says he always wanted to battle a butoh dancer. Sakamoto juts his chin at the challenge and the fight is on, complete with the ringing of a bell.

But the battle really is for sanity and clarity as each man's childhood reveries bubble up. A lonely, thigh-slapping Harris mumbles through "Hush Little Baby." He pops and locks, does the tick where his arm seems made of 40 joints, then the wave when it's as watery and jointless as any Swan Lake Odette. Later, he sings a fragmented "Over the Rainbow," more howl than song. With his expressive hands, face, and full body, Sakamoto recalls watching musicals as a child and astonishes us with a fusion of Fred Astaire as tapper and B-Boy to "Puttin' on the Ritz."

It's to the first heartbreaking notes of Jimmy Scott's cover of Prince's "Nothing Compares 2 U" that they bring us to sadly complicated aspects of their early years and the triumph of their struggles to claim themselves.

In the talkback, North Philly native Harris expressed deep affection for Philadelphia, and how astonished he was to dance recently at the Barnes Foundation, where he recalled the site euphemistically called the Youth Study Center. He said, "Poppers are shape-shifters." And so, it seems, are the names we give to these evolving genres. Butoh originally meant European ballroom dance. Could we now call what Harris and Sakamoto do "buthop"?