Bincho Fields are scatteredeverywhere in the world.It is possible to find all of them before going to the last level. You will need to strike them with Lumina in order to free the trapped people inside. Each Bincho field you break will increase your BP by 5.Here is the list, according to Chapter and amount.

Chapter 2
3 in Steamwood
4 in Somnolent Forest
4 on Twinpeek Mt.
1 while river rafting
1 in Hell's Valley

Chapter 3
4 in Bichotite Mine
8 in Restaurant Basement

Chapter 4
1 on the beach of Dragon Isle
5 in Ice Palace

Chapter 5
3 in the Ant Lairpart of the mine

Chapter 6
1 at the start of the chapter