The National Democratic Party of Japan has voiced support for the proposed supplementary budget. The strategy behind this decision is not explicitly detailed in the headline but it's common for such moves to be aimed at either fostering bipartisan cooperation or seeking concessions in other legislative areas. The timing and specifics of the deal are not known from the headline alone.

In Japan, where majority rule is dominant for legislative decisions, opposition parties often find it strategic to agree to certain majority party proposals, such as budget amendments, in order to push their own agenda forward. It is seen as a necessary strategic move within the complex system of political exchange.

In the U.S. or EU, it is not uncommon for opposition parties to agree on certain issues with the majority for strategic reasons, much like in Japan. The specifics may vary based on individual country's legislative structure, but generally, this is a part of realpolitik - pursuing pragmatic goals often require such compromises.