YOU SAID:
my heart is very oni chan
INTO JAPANESE
私の心はとても鬼ちゃんです
BACK INTO ENGLISH
My heart is very demon
INTO JAPANESE
私の心は非常に悪魔です
BACK INTO ENGLISH
My heart is very devil
INTO JAPANESE
私の心はとても悪魔です
BACK INTO ENGLISH
My heart is so devil
INTO JAPANESE
私の心はとても悪魔です
BACK INTO ENGLISH
My heart is so devil
That didn't even make that much sense in English.