This is for those who didn't read the author note in the synopsis - it really needs to be read to make sense my dear readers:
So the MC- Toji - is from our world, transmigrated into a guy named Toji Fushiguro in DBZ, as since the MC's soul is from our world, the quality is insanely different,
Ki is made up from:
1) Body
2) Soul (Toji's soul quality is insane, traversing and surviving from another entire reality, one that also is able to view this world's (DBZ's) reality's entire history and future before it happens, and so he's got Frieza levels of Potential and starts out -
right as he remembers and that quality resurfaces - at 120 million Power Level like him - same power level Frieza was born with.
It happened because of the amount of Ki Frieza and Nappa exuded, causing Toji's soul to react.)
3) Will (Focus/Willpower. So do expect Toji to make a lot of jokes at his opponents expense- acting cocky, kind of like Vegito, basically emulating him - since Toji knows Vegito is the Ultimate Warrior - to break his opponents focus and concentration and will, to weaken them.)
And the whole improving and then balancing all of it, forming Ki.
So, yeah, because of what Ki is, this is logical. Though do understand- Toji having this potential DOES NOT MEAN HE WILL JUST IN A MONTH BECOME BATTLE OF GODS LEVEL!
I had to go all caps and bold on that so people read it and don't ignore it.
No one knows how Frieza trained after he came back to life, and I sincerely doubt he gained all that power from simply beating up Tagoma for 4 months - plus, logically, training is the breaking down of the body's muscles so that they heal and come back stronger.
Toji's body is designed from the moment the soul possesses it, reshaping it to hold a battle power of 120 mil, the training he'd need would be one that is insane so that his body begins to exert itself and actually break down his muscles - so Toji will mostly grow from fights against those who near him or are equal or stronger than him.
Like Frieza for example. He'd be a good match.
So yeah, hope you stick around and enjoy,
See you all later,
Bye!