YOU SAID:
why were you with raichu?
INTO JAPANESE
どうしてあなたはらいちゅと一緒でしたか?
BACK INTO ENGLISH
Why were you with mechu?
INTO JAPANESE
なぜあなたはmechuと一緒でしたか?
BACK INTO ENGLISH
Why were you with mechu?
That didn't even make that much sense in English.