Responses
I think in this omegaverse (it can differ depending on the author) omegas can only get pregnant if they're in heat, so when they have regular sex outside of heat it's fine
They have had sex without protwction during sachios heat too. Many times.
Honestly with how much Ukano comes inside him they should be parents of 10 rn. Whatever Sachio is taking after having sex must be extra powerful.