Kuzuryū

Kuzuryū (九頭龍, Nine-Headed Dragon) is a considerably large mechanical fortress. Its construction was administered by Yūmei Luenah and constructed deep beneath the Hokage Residence in Tenryūji. Measuring 3/5 the height of the crystal tower concealing it, it can easily contain the entire population of the city, and more within the eight-odd 'castles' sitting at its summit. The remainder of its structure is used as pathways to reach its summit, as well as to house the numerous defensive mechanisms and the alternative systems enabling transformation between ground and air mobility travel modes.

Kuzuryū is powered by Sky Crystals (空結晶, Sora Kesshō), which are maintained within a room located near the center of the fortress. They are crystals containing chakra with the abnormal ability to absorb Natural Energy which with the aid of a Sage Mode practitioner, mold it into Senjutsu chakra to drastically increase its potency. Glossair rings powered by these crystals give mobility to the fortress in either of its forms.

In its ground mobility form, Kuzuryū slightly hovers above the ground. Due to its immense size and the immense durability of its shell easily rivaling the walls of Tenryūji itself, it is capable of mowing through forests with ease. A chakra barrier can be employed around it to ward off attacks, as well as plow through rough terrain and cliffs without leaving a dent. In its air mobility form the fortress hovers at high altitudes.