Ryū (竜,Ryū?) is Japanese for "dragon" and can be found in the Japanese term for "dinosaur" (恐竜,kyōryū?).
Strengths and Weaknesses
A user of this Zoan can become a triceratops—a large, heavy-bodied, herbivorous dinosaur from prehistory—and assume a human-triceratops hybrid form. In Sasaki's case, the full Beast Form is big enough to outsize a 13m-tall robot.
Similar to other dinosaur Zoans, a user of this fruit is granted an enormous boost in physical strength. They can charge into and bash enemies with incredible force, their three sharp-pointed horns (especially their nasal one) serving as a dangerous pointed weapon to pierce opponents with. Given a triceratops' hardy skin, the user also enjoys a dramatic increase in durability, which especially applies to their frontal side that benefits from their thick skull, bony frill, and horns. This durability is such that the user may be unscathed by and able to outright ignore heavy, explosive artillery fire.
While the user's frontal defense is quite formidable, the entirety of their body is not as invulnerable, as seen when the "Franken" was successfully able to damage Sasaki's more vulnerable belly area. Other than that, the user is affected by the standard Devil Fruit weaknesses.
Sasaki uses his ability for combat purposes, particularly against enemies that turn out too powerful for his subordinates to handle alone.
His preferred method of attack in his full triceratops form is charging into enemies head-first, pushing them back and, if possible, piercing them with his horns; Sasaki was able to send Franky's General Franky, an extremely strong robot, rolling back by charging at it. Another time, Franky, inside the robot, was barely able to hold off such a charge and prevent Sasaki's horn from piercing him (though it is unknown if Sasaki would have actually been able to penetrate the General Franky's exterior).
Given his increased durability while transformed, Sasaki can simply ignore any attack too weak to break his triceratops skin, including a nonstop barrage of explosive rounds, sustaining no visible harm from the latter. This can make it difficult for foes to stop Sasaki once he has started his charge, forcing them to dodge instead.
Judging by Sasaki's spiked frill, the fruit transforms the user into the Triceratops horridus species.
Sasaki wielding this ability fits his role as leader of the Beasts Pirates' Armored Division, which mostly comprises SMILE users whose abilities are based on hard-skinned/shelled animals.
Sasaki's favorite food being asparagus seems to be a nod to him becoming a herbivorous dinosaur.