YOU SAID:
Harry Potter was a young magician, who, together with his friends Ron and Hermione, studied in Hogwarts School of Wizardry.
INTO JAPANESE
ハリー・ポッターは、友人のロンとハーマイオニーとともにホグワーツ魔法学校で学んだ若き魔法使いでした。
BACK INTO ENGLISH
Harry Potter was a young wizard who studied at Hogwarts School of Witchcraft and Wizardry with his friends Ron and Hermione.
INTO JAPANESE
ハリー・ポッターは、友人のロンとハーマイオニーとともにホグワーツ魔法魔術学校で学んだ若い魔法使いでした。
BACK INTO ENGLISH
Harry Potter was a young wizard who studied at Hogwarts School of Witchcraft and Wizardry with his friends Ron and Hermione.
That didn't even make that much sense in English.