After retiring as an IBM Distinguished Engineer, he became independent and established the Yamashita Technology & Engineering Office. As a senior architect, he provides technical consultancy support services mainly to major technology companies and SIers. In the industrial field, he has provided various technical solutions to companies, such as architecture of in-vehicle connected systems and quality information infrastructure and IT/OT integration in factory automation, and in the communication field, zero-trust architecture and application architecture of multistage MEC for 5G networks. He is also involved in research on architecture building methodology, service platforms, self-sovereign identity, and generative AI. He has presented many technical seminars.He has served as a technical advisor since the establishment of UMP-JUST, an industry-university collaboration network of the Graduate School of Science and Engineering at the Tokyo University in 2020.