This is another requested weapon from my favorite customer, BooMeister IX so show this guy some love because he's helping me produce more Zanpakuto's for y'all.

My guy, I hope you like this weapon, the only issue is your suggestion of the Bankai appearance, I had absolutely no idea what Raijü tigrine was so I'm just going to take some artistic liberty here.

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Name: Gakugei-in

Translation: Curator.

Weapon Classification: Katana.

Type: Elemental,

Subtype: Aero-Lightning.

Base Appearance: the base form of the weapon takes the form of an ordinary katana but the hilt is a rectangular shape with a emerald green hue, the grip being bright neon yellow.

Shikai Command: "Suffocate"

Shikai Activation Design: Wind surrounds the weapon which starts increasing in speed as well as friction which bolts of lightning starts forming until the lightning transforms into a cocoon of energy before releasing and shows the weapons Shikai state.

Shikai Appearance: Gaku's Shikai form is rather comical if one were to look at it for an extended period of time, it's hilt is a brown leather grip of a massive great sword but the length of the grip is three times as large as any useable or applicable grip could be for wielding a heavy weapon, the blade is also a comically shaped piece of metal, it's shaped as an old time cartoon depiction of a sword, a Diamond Shaped Blade, the user is also seen being covered in Draconic like scales in the skin.

Spirit Appearance: The Appear of Gaku takes the form of a constantly moving and flowing form of a Tiger made from pure elemental water shaped into a Tiger, Lightning crackles around the creature's form as if it was emanating from its core.

Spirit Personality: Gaku is a rather silent creature, not one to strike conversation nor keep one up but it's an incredibly wise creature and spiritual as well and will give advice if it believes it's necessary because if not, it will keep out of its master's affairs nor give input on morality.

Shikai Abilities: Gaku is known for its harmonizing control of both Aero-Lightning Manipulation which is the control of Wind and Lightning Elemental abilities.

The user can utilize both Wind and Lightning Abilities separately which is manipulating the element to create constructs in either element to serve any purpose they have.

For the Lightning Side, They can unleash bolts of lightning at close range or long range, they can also coat the weapon in the energy of the lightning which increases the blades ability to cut and Pierce most defense and material.

The user can also push the lightning into the aerial side and cause a Lightning infused wind shockwave, with enough strength to blow apart a brick wall with ease.

Another trait of the Lightning Manipulation is that they can unleash a barrage of lightning grenades that can be lobbed and thrown which explodes and dealing high force and lightning damage, enough power to scorch skin and deal 3rd Degree Burns and break the ground.

The last trait of the Lightning Manipulation is that they can infuse their own body with Lightning energy to produce a flowing armor of Lightning energy, this ability enhances the users speed to a much greater degree, this also grants the user increased defense to withstand damage from most physical sources.

Now the Aerial Manipulation of the weapon, this allows the user to have a passive boost to their movement speed however this speed doesn't bleed into the users ability of Shunpo thus they don't get an increase of speed when doing the technique.

The user can unleash a variety of wind based techniques that can fit any purpose they have while a couple techniques like the shockwave being the beautiful blend of Air and Lightning.

Another trait that the user can unleash is a massive burst of wind from any point of the body or weapon, this is mainly used to crush the opponent or force the opponent away. It's a good utility for both Offense and Defense.

The last trait the user can do is utilize the healing effects that are present in the wind capable of healing most minor wounds and some of the more fatal wounds however this ability can't recover what's been fully lost like destroyed organs or missing limbs.

Bankai Name: Arashi no sora no kyurêtã

Translation: Curator of the Stormy Skies.

Bankai Release Command:(Optional) Bring the Wrath of the Heavens.

Bankai Activation Design: Wind surrounds the weapon which starts increasing in speed as well as friction which bolts of lightning start forming until the lightning transforms into a cocoon of energy before releasing and shows the weapons Bankai state.

Bankai Design: The Bankai doesn't take an outrageous form like most other but chosen to expand upon its power then its form, it's now a purely colored spear with the shaft being a mixed color of green and blue, like a poorly mixed bowl of paint while the blade being the mixed color of the two which is Teal.

Bankai Spirit Appearance: No Change.

Bankai Spirit Personality: No Change.

Bankai Abilities: the user is now coated in a passive energy of pure red lightning that seems to crackle uncontrollably, this causes immense burning to any within the energy besides the user as such this causes problems when stuck close to allies as this red lightning can harm them during a critical moment so it's recommended by the user to only be surrounded by enemies or atleast no allies close to unleash Bankai.

This energy passively increases the users movement to a much greater degree then what one could achieve in Shikai, the defense is also to a much degree as explained above though can withstand much more damage to even survive a full onslaught by Kenpachi Zeraki with his eyepatch off.

The abilities of both Air and Lightning Manipulation has increased to a degree that both manipulations are now currently mixed to be Aero-Lightning Manipulation which any ability dish out now holds traits of both sides of but the power is increased much much more than what Shikai could unleash.

Bankai is the passive boost of power but doesn't really grant anything new then what's already there.