Akiza Izinski, known as Aki Izayoi in the Japanese version, is a main character in Yu-Gi-Oh! 5D's, and was one of the Signers. She is also called the Black Rose, or Black Rose Witch in the Japanese version.
Akiza possesses an extremely strong special ability which sets her apart from the rest of humanity, and even the rest of the Signers. This psychic ability enables her to materialize and bring to life monsters and the effects of Duel Monsters cards, allowing her to freely control them similar to Yami Bakura and Jaden Yuki.
Initially, Akiza was very insecure and unsure of herself and had a very cold and distant demeanor, a result of spending years being treated as a monster. She viewed everyone around her as her enemy and eventually stopped caring about other people's feelings. It wasn't until Sayer showed her compassion that Akiza began to have hope in her life again. Despite this new feeling of self-worth from Sayer, Akiza's rage at the world continued to grow, which Sayer intentionally drove her towards. After meeting Yusei, Akiza began to question the path she took of distancing herself from normal society. Finding conflicted emotions between both Yusei and Sayer's words, Akiza began to lose her focus and by extension her performance began to slip. When Sayer "died" and Akiza lost her last "place" to turn to, her parents, the people who unintentionally drove her down her hate-filled path, showed how sorry they were for their mistakes and wanted her back with loving intentions. With assistance from Yusei this allowed Akiza to finally find peace and be willing to join normal society again.
After joining Yusei and his friends, Akiza's demeanor has become much more caring, sweet, brave, heroic, kind-hearted, and valuing of true friendship, and she has become more eager to help those close to her whenever possible. Akiza has also developed feelings for Yusei, as Jack pointed out whenever it came to his safety she often gets too worked up. She also cares very much for children, as seen when she stood up to Rudolph Heitmann declaring "I never approve of adults who try to harm children!"
Akiza's telekinetic abilities are that of a Psychic Duelist. This exceptionally strong psionic ability enables her to materialize monsters and effects of Duel Monsters cards. While this psychic power is undefined in the Japanese version, in the dub, Commander Koda states that Akiza possesses telekinesis. It is said that her powers are linked directly to the violent nature of her mind, the reason behind why it had continued to grow over the years. According to Sayer, these powers are far much stronger than even she realizes, since he states them to be superior even to those of the Dark Signers. The full strength of her telekinetic abilities and potential is directly related to her psyche and tendency toward violence, weakening as her violent streak fades. This becomes more apparent after Dueling against Yusei in the Fortune Cup.
Initially Akiza had little control of her incredibly strong telekinesis. She uses a special hairpin ("energy stabilizer" in the dub), to help restrain them. When she completely loses control, the pin gets flung off and her powers increase. After her second Duel with Yusei, she is able to control them for the first time. This is because she wanted to protect her father from the serious great harm that would have occurred from her inability to control her psionic abilities.
Akiza originally despised her Mark of the Dragon, believing it to be the cause of her unwanted power and even noted it as a "wretched mark." She later changed her opinion after her second Duel with Yusei, who believed it to have brought the other Signers together as friends.
In the Pre-World Racing Grand Prix arc, her personality started to lighten up, and so the influence her telekinesis used to have over Akiza has changed dramatically. Akiza is now able to control it, much like Sayer, as demonstrated when she manifested her cards outside of a Duel. This was seen in three situations: when she Summons her "Rose Tentacles" to rescue Yusei, then to bring out Yusei's "Stardust Dragon" to save them from a vehicle dropped onto them, and when she Summons "Black Rose Dragon" to stop Dobocle. In her first Turbo Duel against Trudge, Akiza didn´t cause any real damage to him, pointing out that she can now voluntarily choose not to harm her opponent. During Luna and Leo's Duel against Lester, it was revealed that Akiza can also see spirits, like Luna.
After Team Catastrophe caused her to crash, her psychic abilities disappeared. At first, Akiza felt uneasy about this, but ultimately realized she did not need her special abilities to help people. Ultimately, her powers remained in the form of "Black Rose Dragon"; after her Duel against Sherry, it remained materialized to help protect Akiza, Crow and Sherry from falling rubble. In that instance, it displayed the ability to heal wounds and then it vanished. Akiza also states "Black Rose Dragon" protecting them to be her monster's will.
Her Japanese name, "Aki" has multiple meanings but the most prominent ones are "autumn" and "emptiness", with the former refers to her connection with plant and the latter to her loneliness. "Izayoi" means "sixteen-day-old moon" in Japanese. A sixteen-day-old moon has just passed its fullest phase, so it is at this point that its brightness begins to decline. This is a reference to her age of sixteen at the start of the series.
Her dub name is a westernization of her Japanese name. However, the name Akiza could possibly be a nod Greek Name "Acantha" which means "thorn", referring to her connection with plants. Alternately, it may be a nod to Hebrew Name "Akiva" which means to protect.