First of all, Let me start with the System's grading system;

There are 9 grades the system uses:

[Filthy]

[Lowly]

[Lesser]

[Inferior]

[Superior]

[Elite]

[Royal]

[Grand]

[Supreme]

The higher the Creature's grade is, the stronger it is.

All creatures can increase their grade through evolution, but not by much.

That's where bloodline comes into play.

The Higher a beast's bloodline is, the Higher Grade it can Achieve through evolution.

Now, it is important to make it clear that Grade does not directly mean the Strength of the creature, A creature with a higher grade can defeat a creature of the same level as him but of a lower grade easily, but it won't be able to beat a higher-leveled beast even if its grade is lower.

Beasts with higher grades usually have:

Higher stats.

More Skills.

Better Evolution options.

And that's it.

Higher-grade beasts do not have any authority over lower-grade beasts unless they have exclusive skills which allow them to.

Now for how the [Apex Body] works. (Warning, spoilers)

Apex body lets you upgrade your body through the 9 grades that the system uses.

As those who already read up to chapter 4, Apex body lets upgrade specific Things in specific Sections of your body, for example:

You can upgrade your Eyes in the head section to see better.

You probably saw that Our MC did not have the option to upgrade the grade of his organs, that's because there are only 2 ways to upgrade the grade of your organs:

1: By Buying all the upgrades for the specific section of your body, you may upgrade your organs.

2: Through evolution (as you saw in Chapter 4)

It is also important to note that some Sections have sub-sections, a nice example would be the chest section which has the 2 Sub-sections: the heart, and the lungs(together with the Trachea).

All upgrades up to the Superior are purely Physical, as for Superior and Above- you'll find out later in the story.

(Also, the average grade of a human's body would be Lowly, and Upgrades to lesser if they grew healthily to be a healthy adult)

The System:

The system is not unique to our MC- all of the humans who were reincarnated into the new world have the system.

Classes and Evolutions;

this is actually really simple, Species that have higher wisdom than Vitality at birth will be able to gain classes and upgrade them, and Species that have higher vitality than wisdom at birth will be able to evolve instead.

Example: A human baby has 1 Vitality and 2 Wisdom at birth.

(Note, wisdom does not symbolize Intelligence, read more in the stats section)

Stats:

Stats can be increased by leveling up, growing, and evolving for the Evolver species, and by leveling up, growing, and upgrading classes.

Vitality = Life Force(Health): 1 point equals 10 HP, Evolvers will have 10 HP missing until their first evolution.

Strength = Physical Strength.

Agility = Reflexes and Movement Speed.

Wisdom = Brain Processing power, For example, a person with 15 wisdom would understand something a bit quicker than the same person with 10 wisdom. they will have the exact same train of thought, but the person with the higher wisdom takes less time to think. hopefully, that makes sense.

Dexterity = Control of your body.

Endurance = Stamina, also serves part in deciding the Rate of HP regeneration

Magic = Mana capacity and Mana Regeneration rate.

Skills:

Skills can be gained in many different ways; Evolution, Training, Luck, results of an action, and so on.

Skill Levels:

Most Skills can be Leveled through continuous use, and will evolve after reaching a certain level or when a creature evolves.

Some skills Cannot be leveled, these skills will Have their level Marked as 0 in the status.

Example:

A skill that can be leveled: Glide-1(Number signifies level)

A skill that can't be leveled: Improved vision-0

Skills that can't be leveled can still evolve through evolution or other ways which were not included in the story yet, once they are included, I will add them here:

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A few things about the Story:

I will try my best to make this story realistic, which means:

MC will NOT gain a human form, why? because humans are not a superior species to all creatures, especially not in fantasy novels. Everything in this story needs to have a reason to it, at least most of the time; this is fantasy after all.

I will not make the MC stupid, Especially not having him Hide his powers for absolutely no reason.

MC's Personality:

The MC seemingly adapted to the new situation very quickly, but that's because He does not have the 'soul' of a human anymore, he now has the soul of a beast that was human, he has his memories, but not human instincts. for a bird, there is nothing more natural than doing what a bird does.

Thanks for reading the Auxiliary chapter! If you have any questions, please ask! I will try my best to answer them.