Fairy Tail: Collapsing Stars - Chapter 624 I will take care of it.

One day, Luo Jian woke up from his sleep and found himself in a locked chamber where the door and window were all sealed. A note with a few lines written on it was tacked to the wall: “Escape from this room within an hour, otherwise, you will die.”

There is a sequel called Reincarnation Night (轮回之夜) that takes place in the same universe but has different main characters

- Description from Novelupdates

Nidel, who belonged to the Technological Magic Order that held low prestige, became the bodyguard of a foreign prince behind the scenes. Left with no choice, he assumed the role of a bodyguard, turning into a black cat using the transformation magic he prided himself in, but the one who assumed the role as official bodyguard was the Royal Knight Legato. Nidel, who one-sidedly held feelings of affection towards Legato, thought of this circumstance to be interesting, butー

Lin Yuan took a ‘Gate to All Realms’ and traveled to the vast universe of the Star Sea.

The most powerful person here can destroy the starry river system with a snap of his finger, and tens of millions of light years are coming in a blink of an eye.

Lin Yuan, who has been reduced to the bottom, can only rely on the ‘Gate of All Realms’ and the bound talent ‘Heaven-defying Comprehension’ to travel through all realms and become stronger silently.

[You have incredible understanding, practice the Yi Jin Jing, and understand the ‘Yi Jin Jing, body exchanging blood and quenching the gods’]

[Your understanding is against the heavens, you understand the thunder in your palm, and understand the ‘Thunder Creation and Development Method’]

[Your understanding is contrary to heaven, watching the birth and death of the world, and realizing the ‘world in the palm of your hand’]

[Your understanding is contrary to the heavens, you have studied the art of incarnation outside the body, and realized the ‘Great Law of Self-Transformation’]

…

As he traveled back and forth again and again, Lin Yuan grew stronger endlessly, until… he was invincible in the world.

- Description from novelbuddy

Amid a world war, with his awakening to powerful special abilities (Soul Armor Abilities), Kamiya Yuusuke, conscripted into the military at the age of 10 due to this newfound power, continued to achieve numerous victories on the challenging battlefield. As a result, at the age of 15, he held the position of Brigadier General.Despite traversing battlefields worldwide, he finally managed to return to Japan. The joy of returning home was short-lived, as news of an underage boy in the military started to leak to the public. In response, the military high command ordered Yuusuke to attend a military school called the Special Operations Soul Armor Academy and undergo a revision of his military records.Yuusuke, secretly pleased at the prospect of reclaiming his youth, faced numerous troubles, whether due to the nature of the unique school or perhaps because he had been in constant battle since childhood. What will happen to his relationships with strong-willed girls such as his half-silver-haired childhood friend, the older sister officer who is his work partner, and the tsundere honor student of the same age?