Race: Mamodo/Demon
Gender: Male
Estimated Age: 6-7
Hair: Blonde
Eyes: Golden
Spellbook Color: Red. From Chapter 316 on, his book become golden, and he obtains the ability to use spells of Mamodo who have already been returned to their world.
Spellbook Power: Lightning

Spells
Zakeru: Gash shoots powerful lightning from his mouth
Rashirudo: Creates a shield composed of lightning that deflects attacks back at the opponent with an extra lightning kick.
Jikerudo: Creates a glowing sphere which turns the opponent into a living magnet.
Baou Zakeruga: Forms a huge dragon composed of lightning.
Zakeruga: A concentrated beam of lightning.
Rauzaruku: Amplifies Gash's power and speed for a short time. No other spells can be used while Rauzaruku is in effect.
Zaguruzemu: Spell that charge's anything it strikes with electricity. When an offensive spell is cast the stored electricity explodes. Thus Zaguruzemu increases the power of an electrical attack.
Ganreizu Zakeru: Multiple shots of the Zakeru spell.
Teozakeru: A tremendous blast of lightning.
Baou Kurou Disugurugu:The spell which creates a gigantic dragon arm that crushes the opponent/s.
Maazu Jikerudon: A tremendous Jikerudo which has the ability to block other spells. It traps the opponent within it's center and electrocutes them.
Ekuseresu Zakeruga: A tremendous beam of Zakeruga in the form of an arrow.
Jiou Renzu Zakeruga: A electrified dragon-like creature is summoned, with many electrically-charged parts.
Shin Beruwan Baou Zakeruga: Gash's most powerful spell which summons a gigantic multi-headed dragon crackling with electricity

Gash is Kiyomaro's partner. When he was found by Kiyomaro's father, he had no recollection of who he was or where he had come from. All he remember was his name.