Contract Marriage: The Replacement Groom - Chapter 13: Her husband’s rage

The wife is first, the country is second, and the husband is of lesser importance.

All of his life was spent riding a war horse and accomplishing meritorious military services. But what was the result? In the end, he was cast aside once he had served his purpose.

Out of selfishness, he had favored his consort and neglected his wife. Ultimately, the one who stood by his side was the wife that he had neglected for 10 years…

After being reborn, Jing Shao decided to repent and turn over a new leaf…

Standing outside the door while holding a pillow, Jing Shao gazed at the sky. He must first mend his relationship with his wife. Jing Shao formed a fist and knocked on the door, “Jun Qing, I know my wrongs, let me in!”

- Description from Novelupdates

When The Cute Kunoichis Spied on Their Teacher's Secret is a light novel written by Kazuma Kamachi and illustrated by Ryuushi Tajima.

The story takes place in a world where Japan never ended their isolationist phase, and agents from foreign powers are always threatening to steal the country's advanced technology. In order to combat this threat there has been a resurgence of ninjas that use Strategic Martial Arts, techniques that combine cutting-edge modern technology with a traditional foundation of martial arts and ninjutsu. The story follows Souha Sugiyado, a 17-year old ninja instructor and former ninja prodigy who was forced to retire from active duty by the wounds he suffered in his last mission. Souha's four students are all kunoichi who have all gained the rank of Elite Ninja, the highest official rank available to ninja. However, one day two Shogunate ninja approach him with the news that his four students have gone rogue and have stolen a portable modular nuclear reactor, and thus they ask for his help in bringing his students to justice.

He was very happy to be reborn, but why was he sixteen again, he can’t bear to look back at that time.

Why does he return to being sixteen years old, yet still meet Doomsday?

It’s alright to encounter the end of the world, so why did he have to fall in love with someone?

Even if he falls in love with another person, why did it have to be a man?

Falling in love with a man is also alright, so why did it need to be a secret one-sided love?

Even a secret and unrequited love is alright, so why is that man his….

- Description from Novelupdates