To get race v1 or basically change your race you need access to the 2nd sea(other than draco and the race you get when you join for the first time)
To get race v2 you need to have completed the colosseum quest
To get race v3 you need to have killed don swan
To get race v4 you need to have killed rip indra in the second sea to access the third sea
Now what is this? Well i see that they align with the requirements to get to third sea
Now if you consider that the actual requirement is to have killed rip indra true form then i have another theory
Race v1: you have to have killed the ice admiral to get to 2nd sea
Race v2 and v3: the 2 requirements to get to 3rd sea
Race v4: you have to have killed rip indra true form
Maybe rip indra true form is a requirement for 4th sea??
If you have any opposing theories do say
And if you have supporting theories also do say