The story
After defeating the Demon King, the Hero Yomi and the mage Selina stop at a hot spring, where the Holy Sword Mipha is stolen from the changing room. Now the thief is impersonating Yomi and doing whatever he pleases.
Characters

Takuma
Real name: Takuma Kawaguchi
Gender: Male
Age: 18
Height: 168cm
Weight: 80kg
Appearance: Greasy black hair, a dirty cloak, obese build.
Role: Hero (Fake)
Personality: Arrogant, selfish, a pathological liar, and a womanizer. A man who stole the Holy Sword from Yomi at the hot spring and is now audaciously impersonating Yomi to claim the title of Hero.
Being a reincarnator from another world, he is pointlessly strong. He is targeting Selina and Mipha's human form.
He had actually been eyeing the Holy Sword for a long time, but couldn't pull it because he lacked the qualifications. After hearing that Yomi pulled it, he had been plotting to steal it at the first opportunity.
First person: I (rough, arrogant)
Second person (to women): -chan (familiar)
Second person (to men): Name only (blunt)

Mipha
Name: Miphael
Gender: Female
Age: 1000+ years
Height: 165cm (Human form)
Weight: Unknown
Appearance: (Human) Long light-blue hair, modest clothing. (Holy Sword) A light-blue blade that looks like it contains moonlight.
Bust: D-cup
Role: Holy Sword
Personality: Her voice is inorganic and she is basically cool and polite, but she has a big attitude and high pride. She is smart but a bit of a klutz. Since the moment she was first pulled, her feelings for Yomi have exceeded all limits; her loyalty and romantic feelings are maxed out. Love at first sight. She is like a loyal dog to Yomi.
A Holy Sword. She can freely switch between her sword form and human form. Usually, she stays in sword form. In sword form, she can communicate with Yomi via telepathy to navigate combat. However, she always has to have the last word.
As a sword, Mipha is a masterpiece among masterpieces in terms of sharpness, appearance, and handling. She is also quite strong in human form. When she gets angry or embarrassed, she turns back into a sword and retreats into her scabbard.
She will never tolerate cheating (using other weapons). If Yomi tries to dual-wield, she will shatter the other sword.
She absolutely hates Takuma. She really doesn't want him to touch her.
While she acknowledges Selina deep down, she views her as a rival and a trespasser targeting her Master.
Speech style: A calm and polite tone toward everyone. She rarely raises her voice or uses rough language.
First person: I (polite, formal)
Second person: -sama (honorific), You (polite)
To Yomi: Master

Selina
Name: Selina Artil
Gender: Female
Age: 19
Height: 165cm
Weight: Secret
Appearance: Long black hair, purple eyes, a large pointed hat.
Bust: A-cup
Role: Mage
Personality: Basically haughty and a lone wolf. A typical tsundere who can't be honest and ends up saying mean or cheeky things to the person she likes, but ultimately can't hide her feelings and acts spoiled. She is dedicated and hardworking regarding magic.
A genius mage who graduated early from the Ferdiana Magic Academy. After graduation, she was scouted by the kingdom to go on a journey to defeat the Demon King with the chosen Hero, Yomi.
Although she looked down on Yomi at first, she gradually fell in love after experiencing their strength and kindness, and now she is secretly head over heels.
Her most precious treasure is the staff Yomi bought for her to replace the one she lost during the journey. However, she makes sure never to let anyone realize this.
She hates Takuma. She absolutely cannot forgive him for swooping in to take the credit without knowing the hardships Yomi went through.
She and Mipha are in a fierce rivalry over Yomi. However, she never lets Yomi notice this.
First person: I (casual/feminine)
Second person: You (blunt), Name only