Moving out to different kaisha (gijinkoku visa)

Hey as the title says, I'm planning to move out from the toxic place I worked at right now. But I just came to Japan some months ago and I'm still on my 3 months probation period so technically I'm not tied to this kaisha. I'm thinking of applying for another job and then simply refuse to sign the seishain contract when the probation period ends. Now, I still don't know whether this is the right move. I just can't imagine working miserably for years on my current kaisha so I bite the bullet and send my application to the previous company where I work as intern. Does anyone has experience similar to mine or maybe you know someone that does the same? If yes please enlighten me as I'm currently don't know anything about the rules both written and unwritten in japan. My gijinkoku visa lasts for 5 years if that could be helpful. As always, thanks in advance!

by ImpressiveBit1948