Toaru Majutsu no Index: New Testament - Volume 18, Chapter 4: A Worthwhile Battle at Heaven’s Peak - "Light".

Transmigrated into the world of High School DxD, Roy believed he had been handed a life of luxury and glory. Born into the prestigious Lucifuge family, with his Sister Grayfia as his strict yet devoted older sister, he thought he was destined for greatness. 99,997… 99,998… 99,999… 100,000!!But... reality proved harsher: Roy lacked demonic talent and, despite years of training, remained a Low-Class Devil. his peers effortlessly achieve High-Class status, he’s been trapped in a cycle of endless sword practice and ridicule. Yet, he refused to accept mediocrity. Ten thousand sword swings a day, relentless training.. Until one day..[Ding! The Strongest Demon King System has been activated. Access functions to learn more.]---- High School DxD - Main World!1 - High School of the Dead [●] - First2 - Demon Slayer [●] - Second3 - Akame Ga Kill [●] - Third4 - Bladedance of Elementalers [●] - Fourth5 - Campione [●] - Fifth

In this world, Planet Earth had undergone great changes and humanity is faced with extreme danger. Luckily, humans have something called the Heaven Dao software.

To rebuild death god’s glory, was our obligation!

At the start of the story, he and his zanpakuto had to fight for his own territory!

The Lord of Hell, Mephisto?

Playing with people’s hearts, you might need to learn more from me!

Necromancer?

Let me test the might of Ryūjin Jakka!

Iron Man, Tony Stark?

Come, come, it just happened that I am in need of technical support in the Technological Development Department!

…

Lod, who inherited the will of Soul King, crossed into Marvel World and decided to become the biggest behind-the-scenes manipulator!

When Lod ruled the three major organizations of the Wandenreich, Las Noches, and Seireitei, and looking at the entire universe, he could not help but sigh with emotion: In fact, at the beginning, I just wanted to live!

How could a poor graduate student without any background or connections become successful? With a coaching system? An upgrade? This is not a computer game, but real life we’re talking about!