Yes, Oya Temple makes an excellent day trip from Tokyo. Take the Tohoku Shinkansen from Tokyo to Utsunomiya Station, which takes approximately 50 minutes. From there, it's a 30-minute bus ride or 20-minute taxi to the temple. The entire round trip, including temple visit time, can comfortably be completed in 4 to 5 hours, allowing you to return to Tokyo the same day or explore other attractions in Utsunomiya.