Soul Hackers 2

After fighting the game's final boss, you might be given a choice. Choose "Let her go" to get this achievement. If you don't get all of your summoner's Soul Levels to 100+ and complete all of their vision quests through the 4F of their Soul Matrix, you won't have any optional dialog and this will be the default ending.

Watch the ensuing cutscenes and the end credits, and the achievement will pop when you're returned to the title screen.