A famous Gestalt psychologist Kurt Koffka left a statement "The whole is other than the sum of its parts." Similarly, collective intelligence such as social tagging exposes a social milieu that cannot be obtained from the descriptions of each individual. Previous automatic (or passive) life logging projects mainly focused on recording the individual life activity however, sometimes it is difficult to recollect the situation from their own perspective logs alone. In this project, we propose a social life logging system called "KiokuHacker" (Kioku means memory in Japanese) that encourages the user to describe their life activity by using a massive amount of processed geotagged social tagging from the Internet. The result of a one year user test not only shows that our social life logging system encourages the user's reminiscence which the user cannot recollect by oneself but also indicates that the user evokes their reminiscence which is not directly related with to the tags/scenes the system displayed.