Set of 6 Postal Underlays [Made by the Ministry of Posts and Telecommunications / Post Office]

This is a set of 6 postal undersheets that were distributed to users by the former Ministry of Posts and Telecommunications and post offices before privatization.

The number of undersheets produced is unknown, but it is believed to be a rare item, far fewer than the number of stamp sheets issued.

Details of the 6 undersheets are as follows:

① Special stamps issued in 1982.

② Postal undersheet (with advertisement)
　Special stamps issued in 1982
　Advertisement and donation by: UFO Tsushinsha Co., Ltd.
　*This undersheet is made of thick paper and was received at the Toranomon Post Office in Minato Ward.

③ Postal undersheet (with advertisement)
　Currently issued regular postage stamps
　As of January 1983
　Advertisement and donation by: Yubin Ho Chi Communications Co., Ltd.
　*This undersheet is made of thick paper and was received at the Toranomon Post Office in Minato Ward.

④⑤ Special stamps issued in 1984 (front) / Currently issued regular postage stamps as of January 1, 1985 (back)
　Planning: Tokyo Postal Bureau
　*There are two identical undersheets.

⑥ Special stamps issued in 1988.

These are new and unused items, but as they have been stored by an amateur, there are minor scratches and dirt due to age-related deterioration.
There are no folds.
Please refer to the posted photos for details.

Thank you for your consideration.