TOKYO—Fumio Kishida was reelected as Japan’s prime minister on Wednesday after his governing party scored a major victory in key parliamentary elections. Elected just over a month ago by parliament, Kishida called a quick election in which his Liberal Democratic Party secured 261 seats in the 465-member lower house, the more powerful of Japan’s two-chamber legislature, enough to maintain a free hand in pushing through legislation. The Oct. 31 victory increased his grip on power and was seen as a mandate from voters for his weeks-old government to tackle the pandemic-battered economy, manage the coronavirus, and other challenges. Kishida said he saw the results as a signal that voters chose stability over change. “Now I will focus on promptly tackling various policy measures,” Kishida said after his reelection. Later Wednesday, he formed his second Cabinet by keeping all but one of the ministers he appointed when he took office on …