A theme of Para, the fifth boss of the Haze route.
As it turns out, Para has quite an unpleasant history with Fumikado, with them swapping bodies, among other things. When Fumikado eventually arrives to the Dragonfly Castle, Para is not pleased.
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The soundtrack comes from "Brilliant Pagoda or Haze Castle", 4th part of Len'en series created by Trick Nostalgie. The game is available for free here: http://www.freem.ne.jp/win/game/13429
Trick Nostalgie homepage: http://mugentrick.tubakurame.com/
The soundtrack has been extended to play for 15 minutes.