2021 was a banner year for Fumio Kishida: He held off the competition in the Liberal Democratic Party's leadership race to take the Prime Minister's Office, demonstrated his pluck by daring to dethrone a veteran LDP secretary-general and carried the party to a solid victory in the Lower House election despite what was expected to be an uphill battle.

But that's 2021's success and Kishida won't be able to rest on those laurels for long, if at all.

The prime minister will face another stress test as the head of the LDP when voters head to the polls for the Upper House election, slated for the summer.