Short Summary: Without intending to offend the author, if you come with high expectations due to the reviews this novel has received, I’m sorry to say you’ll be disappointed. At best, and being generous, it’s a novel to pass the time when you have nothing else to read.
Context for those who want an honest review before reading:
The word “Extra” in the novel is just there to ride the wave of popularity for the “extra” genre. The MC is treated like the protagonists of typical Japanese or Chinese novels: he’s always in the right place at the right time to meet the main or important characters for the plot. The other characters exist solely for the MC's convenience.
For example, the MC’s mother knows he was born with an ultra-OP bloodline and tries to keep it a secret by locking him up for the first five years of his life, changing his hair and eye color with magic so no one discovers his original traits. (This is confusing since later on, one of the heroines has the exact same hair and eye colors as the MC.) But then, the mother suddenly lets him go out and explore, leaving him with a caretaker who conveniently allows him to wander off to exactly where he needs to be to meet one of the novel’s main characters—who just so happens to be his age so they can become friends.
In the end, the same overprotective mother inexplicably lets the MC travel with his new friend and his friend’s caretaker, even though there’s no reason for her to trust them after just a few days of knowing them. But this setup was necessary so the MC could be in the right place at the right time to meet another main character and save her.
Even if you try to overlook these plot devices as necessary for the story to progress, some scenes take this to such an extreme that it’s impossible to ignore.
For instance, (keeping in mind that the power system is broken—5- to 6-year-old children are stronger than experienced mercenaries or zone-boss monsters, but let’s ignore that since a character can be as overpowered as the author wants) one of the main female heroines was just passing through the MC’s remote village. Her carriage conveniently breaks down right in front of where the MC is. The MC ends up helping the blacksmith repair the carriage.
The FL (female lead) is accompanied by the strongest human of the current era as her bodyguard, yet for no reason, he vanishes, leaving the MC alone to repair the carriage. This leads to the MC entering the carriage and talking to the FL. After a while, the bodyguard returns and attacks the MC, but the MC (a 5-year-old) easily dodges the attack. The bodyguard justifies this by saying he attacked because the MC was inside the carriage and might be an enemy. Seriously, if he were an enemy, the FL would’ve been dead 100 times over before anyone noticed.
In another instance, the MC and his friend sneak out of their room, even though their caretaker—a supposedly powerful bodyguard for a prince—is asleep nearby and fails to notice two 5- and 6-year-olds escaping through a window just a few meters away. The MC sneaks out to save his friend, who decides to do something foolish by trying to rescue some slaves. Instead of waking the caretaker, who could easily handle the situation, the MC goes alone because, of course, he’s the all-powerful MC who can handle everything.
Conveniently, another FL happens to be enslaved, and naturally, it’s more dramatic for the MC to save her.
In yet another instance, the MC’s friend and another FL, both 5 or 6 years old, free some slaves by incapacitating a group of guards. After they succeed, the boss of the guards arrives, summons his personal guards to deal with the kids, and then complains about how much he lost because of them. Like, WTF, dude, you let them do it, so why are you complaining? But all of this was just to buy time for the MC to arrive and save the day at the last moment.
It’s as if the characters lose all sense of logic just to make the MC look good.
