Lassoo is Mr. 4's gun that consumed a Devil Fruit through some unknown method which allows it to become a living dog. He is classified as a Type D creature, "Small Savage".[4]
Lassoo is a sandy-brown gun, similar to a bazooka, that has handles on the sides and a contoured barrel.
Lassoo is always suffering from some kind of cold that makes him have a running nose and sneeze (which makes him fire cannonballs). It is unknown if this is an actual disease or a side-effect from being an inanimate gun unnaturally absorbing a devil-fruit.
Being a gun that has absorbed a Zoan-type Devil Fruit, the Inu Inu no Mi, Model: Dachshund, Lassoo can transform into a dachshund, becoming literally a gun-dog. In turn, Lassoo gains animal sentience and becomes a mobile mortar, increasing efficiency in combat. During battle, Lassoo functions as an automatic baseball pitching machine of sorts for his master to hit the baseball ammunition with towards their targets.
Cannonballs[]
On Mr. 4's call, Lassoo would cough up a seemingly infinite amount of exploding baseballs that (to Usopp's surprise) are not balls that explode on impact, but when a timer runs out. According to Chopper, Lassoo's baseballs are as heavy as cannonballs, thus ruining Chopper's plan to throw the ball back towards the agents before the baseball explodes. On the contrary, Mr. 4 can use his immense strength to strike these cannonballs with his 4-ton baseball bat, sending them flying at an incredible speed and accuracy at the opponents.
Lassoo was ultimately defeated when Usopp tricked Mr. 4 into slugging Miss Merry Christmas with his 4-ton bat. While Mr. 4 was shocked at what had just happened, Usopp took advantage of this time to fire a hammer at Mr. 4's gut using Chopper's horns as a slingshot. Mr. 4 then flew into Lassoo and hit a stone structure thus knocking them both out. Lasso coughed up one last exploding baseball that completely incapacitated the Mr. 4 team. Lassoo was then arrested by the Marines along with the rest of Baroque Works when Crocodile was defeated.[5]
Miss Goldenweek's "Operation: Meet Baroque Works"[]
When Miss Goldenweek used her Rainbow Color Trap on Lassoo, it is revealed that his dream is to become a tank. Later, when the released members of Baroque Works opened a new Spiders Cafe, Lassoo is shown in his new tank form instead of his old gun form.[2]
When Lassoo "transforms" into his tank form, his name is romanized on his tank. On the right side of the tank is "RA".[6] On the left side of his tank appear the letters "SS", followed by what appears to be either a U or O.[7] As the rest cannot be seen, it is impossible to determine the remainder of the romanization.