I Alone Level-Up (Web Novel KR) - Chapter 5

It was an enormous tsunami that completely covered the sky, and due to its dark water, the sun had been blocked out. A sense of despair ran through everybody as they looked towards the peaked wave quickly crashing down. But was I the only one who noticed the massive sea monster lurking towards the front of the wave? CRASH [Requirments Met] [System has been chosen] [Your god has been selected] [System Granted] [Poseidon System is being installed]

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

A continuation from where High School DxD Volume 25 left off.

He is an undead who is devoid of all humanity, he is the one and only supreme overlord, he is a man who has severe mysophobia.