Both Koei and Tecmo "have excellent financial positions, strengths and the ability to take advantage of each other in order to improve profitability and solidified the foundation of a worldwide leader," according to a Tecmo statement translated by Kotaku.
At the time of the "friendly" buyout offer, Square Enix noted that it would not further pursue the Tecmo buyout if the proposal was rejected.
Whereas Koei is best known for the battlefield-slashing Dynasty Warriors series, Tecmo has been recently defined by its fighting series Dead or Alive and action-heavy Ninja Gaiden games. Both of those franchises were helmed by Tomonobu Itagaki, who recently left the company and sued for unpaid bonuses.
Tecmo's once Itagaki-led studio Team NINJA is still at work though, with three new titles said to be revealed at the Tokyo Game Show.