As the Internet develops, social networking and other communication tools have transformed people's relationships into something fast, visible, and geographically huge. However, these communication tools have not expanded opportunities for acquainting oneself with neighbors outside one's social network; rather, they have comparatively diminished occasions for interacting with unfamiliar neighbors by prioritizing communication with existing friends. Therefore, we invented the medium Ichiyo to increase the opportunities to think of neighbors walking along the same street or in the same neighborhood and to expand the imagination of those who pass by and those who used to be there. Thus, users can engage in indirect interaction. We used commercially available laser cutters to engrave QR codes on leaves that are naturally found in our living space to prevent environmental invasion. The QR codes lead to a communal space on the web where users can freely leave messages. By engraving QR codes, information can be virtually expanded to be presented. To get the feedback of Ichiyo, we let a total of several thousand people experience a new way of communication as a part of the exhibition ''iii Exhibition 2022'', an art exhibition at the University of Tokyo. A total of more than 1,000 leaves engraved with QR codes were prepared and scattered at the exhibition site and along the road from the nearest station to the venue.