isuzu kai ni (swimsuit mode) (kancolle)
The bikini official alternate costume of Kantai Collection's Isuzu Kai Ni, as seen in post #3263053.
Her kai ni-exclusive swimsuit consists of a blue bikini worn with a blue sarong (both containing floral print), single anklet, and a red-white striped innertube containing her anti-submarine rigging.
This tag implicates isuzu_kai_ni_(kancolle) (learn more).