I Received System to Become Dragonborn - Chapter 15 Ambush

Before going to college, an ordinary high school student went to celebrate and got drunk. When he woke up, he found himself in a completely different world. There was a big sect, the approaching sect entrance examination, a slum where his body’s previous owner lived, and a shared memory about a missing young girl.

When he got tangled in a fight with a few punks in this different world, he fell off a cliff and miraculously found himself still alive, with two more voices ringing inside his head. They were Sword Master and Saber Master. In the company of them, he continued to find out more about this whole new world. He took the sect entrance examination, entered the sect, met a strange man in black, and even participated in a major competition of the sect to have a chance to win over his peers!
In this whole new world, he was born again and got to explore the fantastic martial world!

- 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.

Everyone knows that the popular entertainer Song Linchuan is crazy about his little aunt. Since the beginning of his career, he has mentioned her on various occasions.

During an interview with a reporter, he was asked, “What kind of girl do you find most adorable?”

He replied, “Someone like my little aunt.”

The reporter was puzzled.

During a fan visit, someone asked him, “What are your plans after filming this drama?”

He replied, “I’m going back to see my little aunt.”

The fans were confused.

As people across the internet were curious about Song Linchuan’s mysterious little aunt, he brought her on a lifestyle variety show. When she appeared on camera, everyone was shocked to see that she was just a pretty girl in her late teens.

On the show, the young girl had an old-fashioned way of speaking and manners, despite her young age.

When Song Linchuan was too busy to eat on time, she said sternly, “Your body is your most valuable asset. Don’t neglect to eat on time, or you’ll get stomach problems!”

When he stayed up late playing games, she scolded him, “Young people should enjoy their games in moderation. Staying up late is not good for your health!”

The netizens teased Song Linchuan, but they also agreed with his little aunt’s advice.

At a fashion magazine photo shoot, Song Linchuan’s shirt collar was a bit low. The young girl approached him and said seriously, “As a boy, how can you dress so revealingly?”

The netizens laughed and said, “Haha, his little aunt is correcting him on how to be a man!”

Meanwhile, another popular entertainer, Pei Kuang, visited Song Linchuan’s house while he was filming a lifestyle show. As soon as he entered, Song Linchuan pulled him over to meet his little aunt.

Song Linchuan said, “Pei Kuang, this is my dear little aunt. Don’t just stand there, she’s your little aunt too. Call her!”

Pei Kuang was speechless.

A few years later, paparazzi caught Pei Kuang walking with a girl who looked like Song Linchuan’s little aunt, Song Anan. They looked intimately close, and everyone online called out to Song Linchuan, “Look, your good friend is about to become your little uncle!”

At that time, Song Linchuan was in the middle of filming in the deep mountains and had no idea what was happening.