Huckleberry Finn & Tom Sawyer (ハック・フィン&トム・ソーヤ,, Hakku Fin & Tomu Sōya) is an ability that takes the forms of the doll-like creatures known as Huckleberry Finn and Tom Sawyer. With his ability, Twain can shoot with absolute accuracy by attaching either Huck Finn or Tom Sawyer to one of his bullets. Since Huck and Tom's minds are also linked, he can perform long-distance surveillance using them.
(From Bungostraydogs Wiki)