From Overshadowed to Overpowered

After helping the Hero defeat the Demon Lord, four Sages are named Magic Emperors. Sage Ephtal, the Lightning Emperor, spends the next decade training students, including Merlin, a demon baby he rescued after the battle. Eager to take over his school so Ephtal can retire, Merlin rushes her training and foolishly hunts a dangerous monster. Ephtal rescues her using 10th Level Magic, warning her against impatience. Secretly terminally ill, Ephtal regrets never truly mastering magic. His despair deepens when the Flame Emperor publishes research on identifying magical aptitude at birth. Merlin tests as S-Rank for Wind and Water. Ephtal discovers he possesses absolutely zero natural aptitude and only achieved 10th level through sheer, endless training, meaning true mastery was always impossible for him. The heartbreak worsens his illness, and Ephtal passes away. In the afterlife, he remembers he has been reincarnated multiple times. Impressed that in this life he became an Emperor despite having no natural talent, the Goddess grants him yet another reincarnation. Ephtal awakens as a four-year-old with his adult memories intact, determined to master magic. When a dragon attacks a nearby town, Ephtal instinctively destroys it, realizing this time he reincarnated with his 10th Level Magic completely intact.

Ephtal learns he has reincarnated to the same world, 400 years in the future. His father, Duke Orcott, is actually a descendant from Ephtal's past life as the Lightning Emperor. Because Ephtal’s mother is a non-magical mistress, Orcott's other wives banished them to the countryside, where only Ephtal's half-brother, Frasier, supports them. When tests again show Ephtal has no aptitude his mother and Frasier decide he should go to Military Academy. Ephtal discovers magic culture has severely declined; Level 4 is now considered advanced, while Level 9 and above are "Lost Magic." After Ephtal accidentally reveals his power to Frasier, he tricks him into believing it was a dream and agrees to train for military academy. By age 10, Ephtal becomes an expert swordsman, even defeating former Knight Commander Moria using karate moves from a previous life in Japan. Moria, the Headmaster of Azul Military Academy, promises to enrol Ephtal at 15. At 14, planning to run away to a magic academy instead, Ephtal is summoned by Orcott. Orcott proves to be a pompous scumbag obsessed with his Lightning Emperor lineage. Viewing Ephtal as an embarrassment due to lacking magical aptitude, Orcott decides to humiliate him by demanding he duel his sadistic eldest son, Joachim.

Furious that his descendants are such scumbags, Ephtal swiftly defeats Joachim for belittling his mother, Iria, humiliating Orcott. Two weeks later, Frasier and Moria arrive with a baby, explaining that war has erupted with the Southern Barbarians. Amid the chaos, it was revealed that the First Minister plotted to assassinate the King’s newborn son to secure the throne for his own son. To protect the young prince, Frasier and Moria are searching for the main army. They also carry evidence that Orcott conspired with the First Minister to provoke the war. Ephtal joins them, but they are ambushed by Orcott and his personal mage army. When Orcott orders his mages to execute Frasier using a Level 6 spell Ephtal himself created 400 years ago, an enraged Ephtal annihilates the mages with Level 10 lightning magic. He captures Orcott and Joachim, who are hanged by the King for treason. Ephtal discovers Frasier survived the attack thanks to Oberon’s Guard, an heirloom necklace Ephtal owned 400 years prior. Frasier becomes the new Duke, and alongside Moria, agrees to keep Ephtal's Level 10 magic a secret. They support his plan to attend the Magic Academy, though Moria insists on training him in swordsmanship until he turns 15.

At age 15, Ephtal journeys to Krone Magic Academy. En route, he encounters the corrupt, A-rank adventurer Edwards the Mad Flame, who has enslaved a demon girl named Anastasia with a slave crest, intending to abuse her once the crest becomes permanent. When an Orc Berserker attacks, Edwards realises he cannot defeat it and cowardly traps civilian witnesses for the Orc to kill to protect his reputation. Ephtal defeats the Orc and forces Edwards to confess to the attempted murders, which sets Anastasia free from him. Fearing arrest or re-enslavement, Anastasia begs Ephtal to claim her. She reveals she is a descendant of Demon Royalty and distantly related to Merlin, the Academy’s Headmistress, whom Ephtal is glad to realise is his surviving adopted daughter. Ephtal accepts Anastasia as his temporary slave. In the city, Ephtal takes Anastasia to dinner, using the wealth he inherited from Orcott to force the snobby restaurant staff to treat Anastasia with respect. He also encourages her to break her "slave habits" by freely expressing her suppressed emotions by getting angry at him. The following day, recognizing her massive magical potential, Ephtal registers for the Academy’s entrance exam and encourages Anastasia to do the same.

Exam proctor Frantz Bauer announces the first challenge is a battle royale. Ephtal and Anastasia pass after defeating 587 applicants, with Frantz stunned by Ephtal's non-verbal, simultaneous Level 4 spells and Anastasia's level 3 spells. Ephtal misinterprets the written exam instructions and answers all 1,000 questions instead of just the section on Lightning Magic, earning a historic score of 958. Anastasia earns a spot in the Special Class, while Ephtal is named Special Elite Student Representative, a role offering free tuition and a cash allowance in exchange for assistance in public relations and cross-academy cooperation. At Krone Academy, Ephtal spots Merlin, headmistress of Altena Academy, and tries to avoid her. She recognizes his aura and notices his name matches the legendary Lightning Emperor. Merlin accuses him of being the Emperor’s reincarnation, pointing out his exam answers relied heavily on 400-year-old lost magic theories. To protect his goal of mastering magic, Ephtal fabricates a lie: he claims the Emperor had a secret lovechild who founded the Orcott noble family, making Ephtal the Emperor's 13th-generation descendant. To convince a skeptical Merlin, he reveals he knows the Emperor had zero natural magic aptitude. Believing him, Merlin challenges Ephtal to a mock battle, which he accepts, curious about her growth over 400 years.

After an intense duel showcasing their 6th and 7th level magic, Ephtal nearly defeats Merlin with superior skill before she teleports behind him to launch an 8th-level fire attack. Expecting this, Ephtal instantly teleports behind her. Merlin counters with a fourfold 8th-level lightning spell cast from all four hands and feet. Proud of his adopted daughter's progress, Ephtal absorbs her attack using 10th-level lightning magic, neutralizing it safely. Recognizing that only the legendary Emperor possessed such skill, Merlin concludes Ephtal really is his reincarnation. Ephtal confesses to this, praising her as his daughter and moving her to tears. Anastasia interrupts, reminding them the audience just witnessed Ephtal using Lost Magic. Though disappointed Ephtal owns a slave, Merlin trusts his intentions and helps them escape the swarming crowd. Merlin takes them to Ephtal’s former mansion she kept preserved for 400 years. She announces she will adopt Ephtal and Anastasia, transferring them to Altena Academy. Seeing the perks and opportunities available as the headmistress's children, Ephtal accepts to advance his goal of mastering magic.

Ephtal visits his mansion’s secret treasury to retrieve the katana Raikiri, an SSS Rank treasure he took from the defeated Demon King. The guardian, Genie, is unaware of Ephtal's identity and insults him as a thieving brat and Merlin as an old hag. After Ephtal easily claims the sword Merlin appears, prompting the terrified Genie to beg for mercy. Later, Ephtal wins a town-wide treasure hunt to secure a hot springs trip. Anastasia requests a small statue from the prize that resembles Ephtal when he smiles. Merlin notices Anastasia's unique, dangerous slave crest and questions why Ephtal took her in. Ephtal becomes uncharacteristically angry at Merlin and refuses to discuss the matter or abandon Anastasia. Ephtal and Anastasia begin attending Altena, where the students are all demons and elves who consider humans a "lesser species". Ephtal ignores challenges from the demon Abe and elf Maria. Merlin takes over teaching their class, declaring she only cares about instructing Ephtal. The jealous Abe crudely mocks Ephtal as Merlin's boy-toy, but Ephtal remains unprovoked. As inter-class battles approach, Merlin asks for magic-swordsman volunteers. Abe immediately volunteers, and Ephtal is stunned when the terrified Anastasia inexplicably nominates Ephtal to challenge Abe for the position.