Shakugan

The Shakugan(灼眼; Literally translated as "Burning Eyes") is a dōjutsu that is currently and solely used by Reina Sakai, a missing-nin currently imprisoned in Kumogakure. It is a functional but an inferior imitation of the Mangekyou Sharingan. These eyes isn't built based on a real Uchiha's eyes, but rather an imitation concept of Sharingan (the functions) imprinted into a normal eyes, therefore justifying it's existence even though the Uchiha clan is wiped out a long time ago.

Abilities
Although it's an inferior Mangekyou Sharingan imitation, Shakugan works brilliantly well. It grants Reina an access to an unnamed ability that emulates Amaterasu of Mangekyou Sharingan - igniting object upon sight. However, it only generates normal but high-intensity flame instead of jet-black ones. The flames can be extinguished, but it can cause problem to average ninjas. This ability however, didn't work in a place with limited visibility or if the eyes were covered by something opaque (if people assuming that she can burn the eye-cover)

Apart from that, Shakugan also greatly enhances Reina's Genjutsu effectiveness eventhough there are no actual or inferior counterpart to Tsukuyomi or even Susanoo.

Motion prediction ability, as noted by Reina herself is actually 30% of the normal Sharingan. Improvised by Reina's reflex and speed, she caused quite a problem to Hatake Kakashi when they first battled.

Apparently, there's a reason why it's called Shakugan. The Shakugan actually the eyes that gives a person an advanced control and manipulation of flame techniques and notably the Lava Release (熔遁; 溶遁, Yōton; Viz "Corrosion Style" or "Lava Style"), Explosion Release (爆遁, Bakuton), and Scorching Heat (灼熱, Shakunetsu) nature, hence the name Shakugan, the Blazing Eyes. With this ability, Reina developed many techniques that is commented by Hatake Kakashi as "out of this World".

Apparently she hasn't shown any symptom of chakra draining during the usage of Shakugan - a feat Hatake Kakashi is unable to gain as a superior Sharingan user.

During her imprisonment, her eyes were constantly covered all times with an iron cover, and her prison room is located underground, without any lightings as a precaution. Techniques