The workshop to commemorate the retirement of Professor Yoshihiro Chikada was held at the Mitaka Campus of NAOJ. Professor Chikada, known as an inventor of the FX-type correlator, developed a concept of a special purpose computer into gravity pipeline computers (GRAPE) to tackle the N-body problem and greatly contributed to building the systems of the Science Information Network (SINET) and the Astronomy Data Center of NAOJ. His friends from within and outside NAOJ gathered and gave lectures in the workshop. The picture shows Professor Chikada talking about his special field of study.