It takes the form of a normal katana. The cross-guard is a rectangle decorated with a pattern of vertical lines with the long sides pinched in towards the middle. The overall appearance is similar to a squared-off hourglass.
Shikai: Its Shikai command is "Roar" (轟け, Todoroke). Tenken maintains its form as a regular katana.
Shikai Special Ability: In its Shikai, Tenken creates various phantom body parts of a fearsome armored giant to copy whatever body part wielder moves; for example, should wielder swing his sword, a gigantic disembodied arm wielding a sword appears and does the same thing. The body's gigantic parts generated by the Initial Release possess strength and attacking power proportionate to their size (though not as great as it could be due to not having a full body), making the Zanpakutō quite powerful.
Bankai: Kokujō Tengen Myō'ō (黒縄天譴明王, Vidyaraja of Kalasutra's Heavenly Punishment): Kokujō Tengen Myō'ō maintains its form as a regular katana. While in use, wielder and the katana maintain a glow of spiritual energy.
Bankai Special Ability: the Bankai brings forth the entire giant, which is about a hundred meters tall. It wields a sword with a guard similar to wielder's, but with a different blade and with a string hanging from the hilt. The giant takes the form of an armored samurai that copies the movements of wielder to devastating effect, allowing it to deal out colossal amounts of damage. Its strength is far proportionally greater than that of wielder due to its size. Despite its enormous size, it is also deceptively fast, as it perfectly mirrors all of wielder's movements. The Bankai has a critical weakness however; if the giant is harmed in any way, the wounds are reflected onto wielder, essentially making it a bigger target to a strong enough opponent.