YOU SAID:
he jacks off watching the young girls through the window
INTO JAPANESE
彼は窓越しに若い女の子を見てジャックオフ
BACK INTO ENGLISH
He jacks off looking at a young girl through the window
INTO JAPANESE
彼は窓越しに若い女の子を見てジャックオフ
BACK INTO ENGLISH
He jacks off looking at a young girl through the window
That didn't even make that much sense in English.