A young man wanders into the building, business suit, and tie black hair... And a slightly panicked look on his face as he spots a fire starting.
"Gah! What the heck were you guys doing around here anyway!? Geez, that fuse box is a major fire hazard don't ya think... I'll need to talk the owner of this place apparently, but for now."
The man grins to himself, in his right hands is a briefcase, and he'd quickly open it then pull a strange belt out. The belt is shaped like a flask of some kind, even having a cork at the top. After securing it around his waist he'd smirk and place a hand on the cap. An excited tone can be heard from him, despite the flames.
"Time to put out the fire! HENSHIN!"
He uncorks the flask, water begins rushing out of it at a rapid pace. Floating in the air for a moment before suddenly attaching itself to the man, the water would begin to take on a gel form for a while before suddenly becoming entirely solid. After it clears away, he can be seen standing in a suit of dark blue armor, bits of black around the edges, the whole suit almost seems made for movement in the water as much as land. Having something like a sleeker version of an old style diver's helmet upon his head.
"Rushing to the rescue, Kamen Rider H2O."
He'd dash forward, a blue glow taking shape in the man's hands as he points them toward the source of the fire. After a few moments water would leap from them, a burst of it rushing out to slam into the fire and quickly smother it. The stream continues onward as H2O begins spraying all around, the blast of water picking up greater speed. Finally, after a while of doing this he'd have things back to normal, sans being soaking wet, and assuming nothing else happened to make it worse.
"Well then, it seems that something happened here tonight... I don't guess anyone can help me figure that out? Hopefully, this was just a mistake, and not something worse like say, Arson."