Monster in One Piece

Past

Monster celebrated Luffy's madness by going to Party Bar with the Red Hair Pirates after Luffy stabs his own eye.

Marineford Arc

In an attempt to put an end to the Summit War of Marineford, Monster came alongside Bonk Punch and the other key members of the crew, prepared to battle if the war continued.

From the Decks of the World: The 500,000,000-Man Arc

After the time skip, Monster and a few Red Hair Pirates were at the wreckage of an island.

Wano Country Arc

When Monster found out Monkey D. Luffy had joined the Four Emperors, he celebrated with a Bonk Punch.

One Piece Film: Red

Monster was there for Uta’s performance on Elegia.

Egghead Arc

After realizing that the Kid Pirates were challenging them, Monster joined the crew at Elbaf and partied with them. Later, Monster was on board the ship when the crew dropped Marco off at the shores of Sphinx. Later, Monster was on board when Dorry and Brogy destroyed the Victoria Punk and Shanks beat the Kid Pirates on his own.

Monster looked to be a highly happy and carefree person based on his appearance at parties with Shanks and his friends. He is often seen sitting over Bonk Punch's shoulders in the Red Hair Pirates.

Monster looks like a huge monkey with small eyes and a knotted head of fur. He has brown fur across much of his body, like many monkeys, with white fur on his hands, face, and stomach. When he was young Monster was tiny, had beady eyes, and had no topknot.

As a Senior Officer in the Red Hair Pirates, Monster has command over the crewmen. Though he is a monkey, he is intelligent enough to understand people. With Punch, Monster defeats lesser opponents as Punch builds up the power of his own blows to take on stronger enemies.