@JeremyCherfas Personal pronouns in Esperanto are ridiculously simple:
I = mi
You = vi (there is only one form)
He = li
She = ŝi
They = ili
It = ĝi
One = oni (not the same as the number, which is unu)
In the accusative, add -n:
Me = min
You = vin
Him = lin
Her = ŝin
Them = ilin
It = ĝin
Possesives add -a (-aj for plural) and also take the accusative where necessary:
Mia / mian / miaj / miajn
And so forth…