Mio Naruse is a main heroine in "The Testament of Sister New Devil." She is Basara Toujou’s stepsister, a stunning girl famous at her school for her beauty and large bust. Secretly, she is the daughter of the previous Demon Lord, Wilbert, and possesses great magical power. After her foster parents were killed, Mio went through a hard escape life with Maria Naruse before ending up at the Toujou household, leading to a deep bond with Basara and many dramatic events tied to her demonic heritage.
Mio is a beautiful high school girl with a very attractive figure, especially noted for her large bust, which is 90 centimeters and classified as a G-cup.
She has bright, eye-catching looks that make her very popular at school.
Many students are fans of her, and she is called "Princess Mio" by her admirers.
Mio is very stubborn and often acts tough, but she actually has a gentle heart.
She fits the classic "tsundere" type—she gets embarrassed and tries to hide her feelings, but can be sweet at times.
She often says, "I'll kill you a hundred times," but it's more of a catchphrase than a serious threat.
After many times being rescued by Basara, she starts to really like him, though she is shy showing it.
Mio is secretly the daughter of the former Demon Lord, Wilbert, and inherited his powerful magic.
From a young age, Mio lived in the human world, raised by foster parents who worked for Wilbert.
About six months before the story, her foster parents were killed by Zolgear, a cardinal who tried to capture her.
Mio and Maria Naruse escaped together, running from enemies until they found shelter at the Toujou home with Basara.
Mio has very strong magical power, with scarlet-colored mana.
She mostly uses "mana"-type attacks in battle and is an upper-level magic user.
Though her power is great, she started out as a beginner in actual combat because she spent a long time running away.
She can use standard attack magic like fire and wind, and can even create a black hole if needed.
As her bond with Basara grew stronger, especially through the master-servant pact, her power increased fast.
Basara Toujou is her stepbrother and the one she trusts the most.
She relies on him to protect both herself and their home.
After forming a master-servant contract with Basara, Mio's feelings for him deepen, even becoming comfortable with close physical contact due to the pact’s effects.
She gets competitive with Yuki Nonaka, who is also close to Basara.
- Mio’s magic color is red.
- Her bust size is 90 cm, G-cup, and she is very sensitive there.
- She has a fan club at school and is called "Princess Mio."
- Favorite saying: “I’ll kill you a hundred times!”
- Despite being the main heroine, she often has bad luck or tough situations in the story.
Life in the Human World
Mio grew up in the human world thanks to her father Wilbert, the former Demon Lord, who arranged for his loyal followers to act as her foster parents and hide her from enemies.
She did not know about her true identity until after Zolgear’s attack.
Tragedy and Escape
About six months before the main events, Zolgear attacked, killed Mio’s foster parents, and targeted her for her demonic powers.
After this trauma, she lived on the run together with Maria Naruse, who acted as her protector.
Moving in with the Toujou Family
Mio and Maria eventually end up at Basara’s home, asking to live there as part of an arranged plan.
At first, Basara refuses after learning Mio’s secret, but he soon learns the truth and allows her to stay to protect her.
The Master-Servant Contract
To help Mio keep her demon powers in check and protect her from magical threats, Maria suggests forming a magical master-servant pact with Basara.
However, a mistake in the ritual makes Mio the servant rather than the master, which bonds her even closer to Basara.
Battle Training and Fights
Mio starts training with Basara and Maria so she can protect herself.
She gains new strength and confidence through both her feelings and the magic contract.
She fights beside Basara and Maria in key battles, including a match against Takashi Hayase.
Her powers grow as her trust in Basara grows.
Struggles and Trauma
Mio has deep trauma after seeing her foster parents’ murder in front of her.
She is fiercely determined to get revenge on Zolgear and fights hard even when captured.
Many times, magic pacts backfire or other girls interrupt important moments, making her story quite unlucky at times.
“I’ll kill you a million times!!”
Mio's story is full of drama, magic, and emotional ups and downs, making her a memorable lead character with both power and vulnerability.
Despite the tough times, she never gives up on those she cares about.
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