I have seen an other wasp (I'm in Japan) than the 'giant killer hornets' killing (decapitating) what looked like either another wasp/bee either a bee-looking fl

I have seen an other wasp (I'm in Japan) than the 'giant killer hornets' killing (decapitating) what looked like either another wasp/bee either a bee-looking fly. It was quite a small-scale wasp, a black one with narrow white stripes, but its technique was very good. It just dropped next to where I was sitting holding its prey which was trying to escape.