Restoration works for restart of the experimental fast reactor Joyo need to retrieve the bent irradiation test subassembly (MARICO-2) left in the in-vessel storage rack and replace the damaged upper core structure (UCS). In-vessel visual observations using radiation resistant fiberscopes and cameras were conducted to investigate the MARICO-2 and the MARICO-2 was temporarily lifted to confirm the condition. The in-vessel $\gamma$ ray dose rate was measured to evaluate the activation of the UCS which will be reflected to optimize the shielding design of a UCS replacement cask and a MARICO-2 handling tool.