Iku Iku no Mi

Belonging to the Paramecia branch, the power Biblo swallowed lets him swell non-living things under his charge to towering size, as if the objects were creatures that could grow. The feat earned him the title of Nurturing Owl. Its name traces back to ikusei, a word for rearing, nurture, or cultivation, whether of children, beasts, or plants. Biblo applies it as head of the Owl Library on Elbaph.

Simply crossing into the wielder's domain appears enough to start something expanding, and the change can strike at once, shown when a volume Nico Robin held enlarged the moment she entered the Owl Library. Anything grown this way can be reverted to its former dimensions, but nothing may be reduced past the size it began at. That one-way rule tilts the fruit toward giants, since a human or a comparably sized race ends up wrestling with the oversized results, and both Chopper and Jewelry Bonney struggled to read an enlarged book. What triggers the effect seems to be proximity and the librarian's care rather than any touch, though the exact rules, ranges, and ceilings are never spelled out. The user is still bound by the ordinary handicaps that come with a Devil Fruit.

Biblo stands as the sole wielder, working as chief librarian of the Owl Library on Elbaph. His mere presence upsizes books once made at human scale into editions the towering locals can read and handle with ease, a purely practical rather than combative use. Two related fruits invite comparison. The Deka Deka no Mi enlarges only the eater's own body, while the Moa Moa no Mi, a non-canon fruit, briefly grows whatever it touches. There is also a naming curiosity here: the Grow-Grow Fruit, its official English title, is the only reused Devil Fruit English name, matching that of the Mosa Mosa no Mi.