Kageborne Key Bindings

These are listed under the "Kageborne" category in Controls. Default key, in-game name, and what it does:

J, Open Shinobi Menu: opens and closes the Shinobi Menu.
R, Combat Mode: toggles Combat Mode.
G, Chakra Control: toggles Chakra Control.
Left Alt, Ninja Dash: dashes.
X, Substitution Jutsu: uses the Substitution Technique once you've learned it in the Ninjutsu tree (80 chakra, 15-second cooldown).
Right Arrow, Next Jutsu Slot (move right): moves the loadout selection to the next filled slot, or, with a release in hand, to the next jutsu on its bar.
Left Arrow, Previous Jutsu Slot (move left): the same, backwards.
M, Meditate: sits down to meditate, or stands up.
B, Tailed Beast Mode: a jinchuriki enters their beast mode.
Y, Stage Up (Susanoo / 8 Gates / Tailed Beast): steps a Susanoo up, opens the next of the Eight Gates, or steps a jinchuriki's form up.
H, Stage Down (Susanoo / Tailed Beast): steps a Susanoo or a jinchuriki's form down.
N, Eye Evolution Wheel (hold): hold to open the eye wheel and pick a dojutsu stage, and release to choose (only if you have eye stages).
K, Sharingan Lock-On: locks onto a target. While locked, the view eases round to keep it centred.
I, Cast Copied Jutsu: casts the jutsu you stored with Sharingan: Copy & Store Jutsu (copying itself is a jutsu on your bar, not a key).
Up Arrow, Sharingan Stage Up: steps your Sharingan one stage up, in the same order as the eye wheel: from closed eyes to the first tomoe, then each further tomoe you have, then each Mangekyo you have.
Down Arrow, Sharingan Stage Down: steps it one stage back down. Going down from the first tomoe closes your eyes.

Both only work if you have a Sharingan, and only step through stages you have unlocked.
Each change of form plays a short tomoe spin on your eyes, which other players see too: the iris spins into its new form, clockwise going up and anticlockwise going down. It plays the same way when the Sharingan opens or closes, gains or loses a tomoe, or opens a Mangekyo, however you changed it.

Unbound, Practise Hand Signs: replays the hand signs of the jutsu you last practised in the menu ("Practise a learned jutsu from its details in the Shinobi Record first." if there is none).
Unbound, Swap Camera Shoulder: flips the camera shoulder.

Casting Without a Cast Key

There is no cast key: in Combat Mode, right-click casts.

Fixed Controls

These can't be rebound:

Y / N answer a village invite while its banner is up and no screen is open.
W A S D answer prompts in the meditation minigame.
Left click (attack) is taken over in some states:

Riding a great summon or tailed beast: left click makes the creature attack, and holding right-click charges its special (such as a tailed-beast bomb), released when you let go.
With a Susanoo out that has arms: left click drives its combo.
While holding Chidori or Rasengan in hand: left click drives it home.
Riding the Kannon: a flurry of fists.
In the eighth gate: left click is Evening Elephant.

Inside the Shinobi Menu: J or Esc closes it, and Tab or the arrows navigate.
F5 cycles to the shoulder camera (vanilla's rear third person).