Dragon Quest - Dai's Great Adventure [Manga]

Dragon Warrior: Dai’s Great Adventure (???? – ?? Doragon Kuesuto – Dai no Daib?ken?, lit. Dragon Quest – Dai’s Great Adventure),¹ is an original manga based in the fantasy world of the video game series Dragon Quest. It was originally created as a two-chapter short story titled “Derupa! Iruiru!”. Its subsequent success led to the three-chapter sequel “Dai Bakuhatsu!!!” (Dai Explodes!!!), and later the serialization of Dai no Daib?ken.
The manga later spawned an anime series, which would be the second one based on the Dragon Quest franchise, Dragon Quest: Yuusha Abel Densetsu (known in America simply as Dragon Warrior), being the first.

The story starts with a young kid named Dai remembering a story told to him by his adoptive grandfather, the monster magician Brass, about the defeat of the Demon King Hadlar by the hands of a hero known as Avan.
After the defeat of the Demon King Hadlar, all of the monsters were unleashed from his evil will and peace reigned supreme around the world once again for 10 years. Some monsters and demons moved to the island of Delmurin to live in peace. Dai, the young protagonist of the series, is the only human living on the island. Having been raised by the kindly monster magician Brass and with his best friend, the monster Gome, Dai grows up to dream of becoming a hero. The true story begins when a very special person arrived at the island to meet with Dai: Avan, an instructor of heroes who came to the island to teach Dai, by request of Leona, a princess who was previously saved by the boy.
Avan offered Dai a full week of difficult training which would create a hero out of him. Having just learned the second of the three secret sword techniques of Avan, Dai’s training was interrupted by the Demon King Hadlar, believed to be dead. Hadlar announced to Avan that he worked for an even more powerful evil king who resurrected him, the Great Demon King Vearn. Weakened by the spells he used to help Dai on his training, Avan nevertheless confronted Hadlar. To protect his students and destroy Hadlar at the same time, he cast a spell called “Megante” (Sacrifice) which required the caster’s own life force to be used. Sadly, the spell did not destroy the Demon King as Avan had planned and Dai, Pop, Brass and Gome were left to fend for themselves. Only the awakening of a hidden power within Dai, symbolized by the appearance of a strange mark on his forehead, saved the day, causing Hadlar to flee. Dai decides to leave the island with Pop to avenge Avan and defeat the Demon King and his master to bring peace back to the world.