AKS has filed a lawsuit against the two men assaulted Maho Yamaguchi last December.
A 3rd party independent council investigated the assault earlier this year. The company has been considering pursing a civil case against the men since the council's findings.
The two men being sued were arrested by the police in December for assaulting Yamaguchi. They were released without being charged.
By taking the two to court, AKS hopes to create more clarity and transparency regarding what happened.
The company's action against the assaulters comes after months of criticism for the way it has handled the case. NGT48's reputation has suffered greatly in this time, ultimately resulting in the group having to dissolve and restart anew.
Yamaguchi will be leaving NGT48 on May 18.