It looks like the government's PR effort to show that the Reactor 4 spent fuel pool and the top floors of the Reactor 4 building are not toppling over.
Vice Minister Ikko Nakatsuka is a DPF politician elected from Kanagawa Prefecture. He is also the Vice Minister of the Reconstruction Agency.
From TEPCO's Handout for Press, 4/23/2012:
Support structure underneath the Reactor 4 Spent Fuel Pool, on the 2nd floor. The vice minister is on the left (his name is on the Tyvek suit):
Reactor 4 Spent Fuel Pool on the 5th floor (I suppose it is buried under the white plastic sheet):
The worker who still tweets occasionally from Fukushima I Nuke Plant is saying they are removing the columns on the top operation floor of Reactor 4.