Pull inside a submerged office. The Angel advances outside the window.
The part that looks like a face comes IN, and it continues going by. The gill-like parts come into view.
Reichu: Notice the gill-like structures on the legs. A very interesting design touch, in my opinion; you don't see too many humanoid characters whose respiratory system is located in their thighs and hips. There's a good closeup of these structures later (C-098), but even here, you can see that they are essentially three valved lids that contain and protect the feathery reddish gills within. They apparently serve a double purpose underwater — take in oxygen (since evidently Sachiel does breathe) and help propel him forward. Pretty cool, no?
Shin-seiki: (001~004) A very efficient opening sequence. It quickly lets us know that it's 2015 and the world is quite a different place: The coastal cities are underwater (a very common trope in futuristic anime) and really weird-looking, big, green things are on the loose…