YOU SAID:

What if this X person was the killer?

INTO JAPANESE

この X 人が何キラーか。

BACK INTO ENGLISH

This X-men where killer.

INTO JAPANESE

この X-メンがキラー。

BACK INTO ENGLISH

X-men is a killer.

INTO JAPANESE

X-メンはキラーです。

BACK INTO ENGLISH

X-men is a killer.