such contradiction is happening? Although we can contact easier and get information a lots, we feel it is still very difficult to tell a person/content we get to know is trustworthy or not based on much information we have. It is simply because all are free and unlimited. Registration accounts on SNS is free. Posting text, image, or even videos is free. Click like, share posts, retweet are all free. Also, it is unlimited. You can click like 1,000 times or more a day. Both getting followers and follows are unlimited. For example, if someone has more than 100,000 followers, we do not know whether he/she has really 100,000 funs or not. Out of 100,000 followers, he/she may have only 1,000 funs and rest of it might be anti-followers. It often happens. No one knows for a fact. For most of consumers, we think NES (Nintendo Entertain- ment System, Family computer) released in 1984 was the first computer. It became very popular worldwide rapidly. Super NES, Play Station (SONY) were released in 1990 and 1994, respectively. At that time, issues of software developments was limit of memory. ROM (Read only Memory) was very expensive. For example, the first RPG, Dragon Quest, released in 1986 was provided by only 64KB. It was amazingly just 64KB. If you take a photo on iPhone, one shot is larger than that. In 1995, we all recognize internet revolution by Windows95 and Yahoo!. So did we. Before those launches, most of us did not understand how to use Internet. In 1997, Google appeared. We had gotten a wing to fly Internet. But it was not easy. The only way to get connection with Internet was dial up. Its connection speed was only 28.8Kbps. Although internet is new generation of technology, all were inconvenient. The first broadband called ADLS (Asymmetric Digital Subscriber Line) was introduced by Yahoo! Japan, a group of SoftBank in 2001. They provided ADSL modem by free to consumer. Internet connection speed became fast to 2MB to 4MB. We may say that it was the first freemium economy on Internet. Simultaneously, CPU performance was improved for example, from 150MHz of Pentium in 1996 to 1.3GHz of Celeron in 2002. Gradually, we are able to do various things on Internet. In 2004, Facebook was released. No like button at the beginning absolutely. No function of posts, share, nor message. All users can do is only post one photo and input their occu- pation for example name, birthday, grades only. Facebook has released free function one by one in line with the development of Internet. In 2006, the word of Web2.0 was paid attention to. Its keyword was free. As of 2019, most of people think it is normal. It is surprising that posting text, photo, or video on social network services are free. If you post a single video, you would consume 10MB. Its size is similar with the size of 100 games on NES. Business model of Web2.0 players is advertisement model. First of all they need to gather users, views, and impressions. That is why they provide their services by free to get impressions more. In addition, they had to provide functions that users can not help but use. The first one was like button released in 2010 on Facebook. Since they need impressions more, users can click it unlimitedly. Most of all functions are free and unlimited. Is it good features of Web2.0 services. However, it is also harmful function ironically. It lead rapid expansion and social changes. Arab spring in 2010 was said to be brought by SNS. It also caused large amount of fake contents and excessive criticism. Web2.0 model is approaching a corner. We believe that it is time to re-build the current social web. We have an idea to solve these issues. It is bajji. II. SERVICE CONCEPT OF BAJJI A. Visualization of trust BAJJI is a new generation of SNS using blockchain technology. What we are trying to do is visualize trust between people. For the last five years, variety of C2C services like Uber, Airbnb and Mercari have been appeared. We become to be able to select someone we do not know on those platform. Why we could choose someone? On Uber, it sounds dangerous you can take a ride on a car which driver you do not know. You can stay somewhere even though you do not meet with its host. Why we could select unknown person? It is because we see rating. You just check its rating. On such apps, rating of drivers, hosts, or providers are disclosed. When you take a cab on Uber, you do not see drivers basically. What you see is only rating. It is just number. Once you get off the car, you can not tell name of the driver any more. Rating is a kind of credit. Credit is built by past perfor- mance. Most of all C2C services rely on rating. One says that we entered big data era. However, no data regarding to trust is stored yet. Trust is built by reputation or expectation gained from family, friends, or colleagues. It is also established by honest behavior. Once such trust data of each person is stacked one by one on SNS, we never see fake news nor excessive criticism. Visualization of trust will lead to solve big issues on the current social web. Since one’s trust is built by others, visualization of trust would be deterrent to go wrong. bajji is named after a badge which is symbol of trust. A badge is used for lawyer, police, and member of parliament etc. Our service concept is giving bajji as symbol of your trust to someone you would like to convey your mind or sympathy. Its transaction is recorded on blockchain which will be never tampered. Important thing is that bajji is limited. It is not free nor unlimited. New users on bajji will receive 30 (to be fixed) bajji only first. Since it is limited, users have to consider to use it. As a result, the number of bajji you received will stand for your trust from others. B. Backgrounds of designing bajji services Our vision for bajji is building trust-based world through blockchain technology and providing innovative services to TABLE II CREDIT AND TRUST Credit Trust Honestly rating Reputation Expectation