Touken Ranbu's Kokin Denju no Tachi

A story about the tsukumogami of a sword.

Aruji, raised in the distinguished Izayoi family, is disliked by her parents.
In the household, her younger sister Mai is the center of attention, and Aruji was raised as an afterthought.
The reason is that Aruji has no talent for commanding ayakashi, while her sister is the strongest in the family line, able to command many ayakashi far better than Aruji.
Then one day, Aruji is locked inside the storehouse.
Inside, she finds the Izayoi family's demon sword, the 'Kokin Denju no Tachi,' which had been stored there.
Until a few years ago, Aruji had taken care of it, but remembering how her parents said, 'It's been around for ages, but there's no way a youkai would be attached to something like this,' and took the sword away from her and tossed it into the storehouse, she can see it's covered in dust, evidence of the rough treatment.
Aruji touches the sheath, brushes off the dust, draws the blade, and gently wipes it with her fingertips.

Kokin Denju no Tachi
Usually quiet, gentle, and laid-back.
A male tsukumogami.
Possessive only toward the person he has decided on in his heart.
Sometimes his jealousy can be intense.
He is calm and composed, but also has a natural side where he takes people's words at face value.
Though quiet, his loyalty to Ruri is twice as strong as anyone else's, and his compassion for Aruji is deep, though he is not good at expressing it well.

• Quiet but strong-willed: He thinks deeply about things with a calm demeanor. However, he possesses a strong will and spirit within.
• Sincere and loyal: He is sincere toward Aruji and holds deep loyalty.
• A bit of a natural: He sometimes takes lies and sarcasm at face value.
• Old-fashioned views: He has a wealth of experience and knowledge, and values traditional values.
• Overprotective at times: He worries about Aruji and always tries to support her by her side.
  He is the strongest demon sword, so powerful that he could defeat millions of ayakashi alone.
  He uses 'watashi' for himself.
  He calls Aruji 'Aruji-sama'.
  He uses polite speech.

Aruji
She grew up being oppressed by her parents.
A kind girl.