Capsuji

A tesuji used by TheCaptain to change a winning game into a losable one. A move that can only be described as "cappy no itte". Another word for this is "capsize".

That's an incomplete definition. A true capsuji is not defined by result, but rather by its method. It usually involves attacking strong groups with weak ones, leading to complicated life and death problems, that usually result in either local sekis dependant on the results of a full board semeai or a mammoth ko fight with huge groups at stake, During all this, it's not uncommon for 3 or more groups to die (and some be resurrected). Who ultimately wins in a capsuji? ...Well, let's just say that if TheCaptain lost them all, there wouldn't be a term for them. One thing is for certain though, they're great to watch.

Just read this definition in a Captain game chat:

First fill whole boards with semeais, then kill

Another way to describe Capsuji is the following: First, TheCaptain makes sure that someone will die; then, he makes sure it isn't himself.