The Japan Cloud Foundry Group, a user group in Japan, has been carrying a project named "Cloud Foundry 100-day Challenge" ("Cloud Foundry 100-nichi gyou" in Japanese, "gyou" originally means a kind of discipline or training in Buddhism). It is an activity to make 100 open source apps run on Cloud Foundry (CF, hereafter), one app per day. The main objectives of this project are as follows: 1) Let application developers know about the features of CF; 2) Find essential points to make a variety of apps run on CF; 3) Develop application developers' requirements to improve CF, 4) Collaborate OSS developers to make their apps "CF-ready". At the present moment (9 Sep), we've finished 57 apps. In this talk, I will share various (somewhat unarranged) experiences and knowledge got from the project.