Board Thread:Game Updates/@comment-3502824-20170721030939/@comment-27099106-20170731113410

The Body Robber wrote: 13▼駆逐艦「海風」に【水着】mode期間限定実装 改白露型駆逐艦「海風」に今季新作の【水着】mode、期間限定実装です！ 海風提督の皆さん、大変お待たせ致しました！「海風」は今季の夏イベで、前段作戦海域でも邂逅できる予定です. また、彼女には【夏】ボイスも実装です！

I think this says Umikaze will drop in additional maps appart from just 6-5 (appart from saying she gets her CG and some voice lines)

but google translage sucks at japanese so i cant say for sure and when i saw it, i was guessing that it is the event's Main Ops maps, towards the earlier maps e.g. E-3 or E-4. though, it could also be just before the EO.