Named after a river in Chibu province. ("Yahagi" literally means "fletcher".)
She tends to speak in a serious tone, with militaristic terminology. (Which is strangely uncommon in a group of warships.) She has a line about enjoying Sasebo burgers (served at, and named after her hometown) as an uncharacteristic mundane side to her, however. While she acts mature around her sisters, she tends to play an awed junior to (or romantic interest to) Yamato.
Yahagi has long black hair tied into a ponytail with a red scrunchie and has notable sidelocks and red eyes. She and her sisters wear a sleeveless serafuku that exposes her midriff with a red pleated skirt, which vaguely implies the sort of miko outfits that the battleships wear. She wears a necktie, gloves, belt, and has uneven legwear where the left leg has a single thighhigh stocking on a garter strap.
Her combat gear includes a bridge, smokestack, and mast worn in a backpack-like arrangement, with two swing arms carrying twin cannons on three turrets controlled by joysticks on their side. She has another turret on her right ankle, and a flight deck on her left leg, and wears armored boots.
Yahagi Kai Ni
Yahagi is the second of her class, after Noshiro, to obtain her second remodel on March 31, 2021, although her getting a second remodel had already been known before Noshiro's through a series of trailers for the second Kantai Collection anime, starting with the one shown at the Kancolle Jazz Concert Festival in 2019. See the article for more details.
The historical IJN Yahagi was sunk by American aircraft a couple months before the end of the war off the coast of Kyushu in the horribly ill-fated and ill-advised "Operation Ten-Go", which sank Yamato and virtually everyone else involved. (Her militaristic/dutiful personality is probably in homage to the "dutiful soldier" who knowingly goes on a suicide mission like Ten-Go. Ten-Go is especially romanticized in Japan as the symbol of the fall of the IJN.) At the time, she was leading DesRon 2 (a destroyer squadron). Because of this, she almost always appears either with Yamato, her sister ships, or guarding destroyers.