What is Kisama?
1.
Japanese has varying levels of politeness - this is the most impolite way of addressing someone. Could roughly translate as "bastard", "scum" etc.
Motoko from Love Hina: Urashima! Kisama wa honto ni chikan desu!
Urashima, you bastard! You're a real pervert.
2.
Literally "precious sir" in Japanese ("ki" meaning precious, "sama" being a very polite honorific), it is what a samurai called his enemy. In modern speech, it can be used with someone you want to kill or as an extremely rude insult. Has been used by soldiers and yakuza. Sometimes used liberally by english-speaking otaku.
"kisama!"
"oh no you didn't!"
See