Chopper's left antler has a metal plate wrapped around it at all times. He originally broke it while retrieving the mushroom for Doctor Hiruluk. It is unknown how his left antler manages to transform during his transformations; given that they disappear completely during his human form, one can assume the devil fruit's power is capable of doing this. Chopper's reindeer appearance often comes in handy. Enemies will usually assume he is just a pet when they haven't actually interacted with him. This was especially useful in Alabasta when he played an instrumental role in Sanji breaking the others out of Rain Dinners.
The name "Tony Tony Chopper" is partly a play on "Tonakai" ("Reindeer"), and partly on the idea that his horns look like they could chop down trees.
His birthday is Christmas Eve.
Whenever he is complimented (especially by a human) he usually screams and swears sulfurously at them. However, his body language belies what he's yelling as he claps his hands and smiles broadly.
Freak of Nature
Hiriluk overwhelmed with tears of gratitude, ate the mushroom to show his love and appreciation to Chopper, but Chopper would later find out from Dr. Kureha that he had given Dr. Hiriluk a fatal dose of poison. But Hiriluk was not to live much longer, anyway. Declaring that he had had a wonderful life, he committed suicide by blowing himself up outside of Drum Castle (before being killed by the poison, for Chopper's sake), where he wanted to heal the sick before he died. As per Hiriluk's last wish, Dr. Kureha (the last remaining doctor not owned by King Wapol) took Chopper in and taught him 'real' medicine for the next 6 years. Chopper worked as hard as he could, in order to become a doctor like his idol, Hiruluk.
Arrival of the Straw HatsHowever, Chopper's isolated life in Drum Castle (which he and Dr. Kureha annexed after the King Wapol fled) would one day come to an end with the arrival of Monkey D. Luffy and his pirate crew. Chopper, naturally distrustful of humans, was not pleased, especially given Luffy and Sanji's desire to cook and eat him. But when Chopper showed both his medical powers and his skills in battle against the returned forces of King Wapol, Luffy offered (forced) him the (as-yet unfilled) position of Ship's Doctor in his crew. While Chopper was at first unwilling to leave, he remembered Dr. Hiruluk wishing Chopper to sail around and seeing the world on his own and with his desire to broaden his medical horizons, he decides to join Luffy and his crew. Fleeing the castle with the Straw Hat Pirates, Chopper was given a send-off of gigantic proportions: Kureha had turned the snow into Sakura blossoms, and the cliff where the castle stood became the sakura tree the very same that Hiruluk had researched over 30 years that would one day, cure the people of Drum of their "sickness of the heart", passed to Dr. Kureha as one of his last request before death. Overcome with tears, Chopper made a fond farewell to his birthplace and mentors, setting out to sea for the first time in his life.
- Walk Point (脚力強化 (ウォーク�?イント)): This is Chopper's form as a normal reindeer, useful for general travel on foot. Called "Sprint Boost" in the English dub.
- Brain Point (頭脳強化 (ブレーン�?イント)): Chopper's usual look, with a small body and large head. He is smarter in this form, and also inexplicably cute. In addition, he can scope out an enemies weakness in this form, while he is under the influence of a Rumble Ball. In the English dub it is named "Brain Boost". This is also the form where he does his best strategizing, as he can utilize both human intelligence and reindeer sensitivity at the same time. Even though this form appears to be his normal form when not under the effect of the rumble ball, he has only average intelligence.
- Heavy Point (�?�?強化 (ヘビー�?イント)): Chopper's "human" form, which gives him a werehuman-like appearance and height. He uses this form to help steer the ship. Called "Heavy Boost" in the English dub. This form imbues Chopper with super-human strength. While his voice stays the same in all forms, his voice becomes deeper in this point in the English Dub.
- Jumping Point (飛力強化 (ジャンピング�?イント)): Chopper keeps his reindeer legs in a human-like form, which allows him to jump long distances. "Jumping Boost" in the English.
- Arm Point (腕力強化 (アーム�?イント)): Chopper's second most powerful form, his fore-hooves become extremely muscular in his humanesque form, powerful enough to inflict a great amount of damage. In the English version, this is called his "Arm Boost"
- Horn Point (角強化 (ホーン�?イント)): Similar to Walk Point, but Chopper's forelegs get bulkier and his horns get larger and sharp. Chopper first uses Horn Point against the Mr.4 team, labeling it his "most powerful form". In the English version it is called "Horn Boost".
- Guard Point (毛皮強化 (ガード�?イント)): Chopper's fur grows out and becomes an impenetrable shield against outside attacks. He looks like an overgrown Chia Pet in this form. In the English version it is named "Guard Boost".
It seems that the consumption of three Rumble Balls in under six hours created a new transformation, in which he is standing similar to Heavy Point, but possesses an oddly misshapen head and antlers, as well as an incredible (likely more than twenty feet, or about the size of an office building) increase in height and strength. Chopper's fur is also lengthened in this form. Chopper also loses all consciousness and goes on a berserker rampage in this form. He appears to look like a traditional Japanese B-grade movie monster. Also, this form appears to be a combination of all Chopper's points, not including Brain Point (Heavy Point stance, Arm Point strength, Walk Point speed, Horn Point horns, Jump Point legs, and Guard Point hair). The limits of Chopper's strength in this form are unknown, but while in Monster Point, he defeated the very powerful CP9 member Kumadori with a single blow