The ship escorted a convoy from Kwajalein to the naval base at Truk in January 1942, where a sponson was installed for a pair of license-built Type 93 anti-aircraft machineguns on the forward side of the bridge. "Yayoi" then escorted a troop convoy from Truk to Guam later that month, and then joined the invasion of the Solomon Islands, covering the landings of Japanese forces during Operation R (the invasion of Rabaul, New Ireland and New Britain), and during Operation SR (the invasion of Lae and Salamaua on New Guinea) in January–March. From 28 March to 1 April, she participated in the initial occupation of the Shortland Islands and Bougainville in the Solomon Islands. Later that month, the ship supported the occupation of the Admiralty Islands.