The Mental Model (human avatar) of the Fog heavy cruiser Takao. After Gunzō defeats her in battle, Takao falls in love with him and later joins the Blue Steel fleet. She is almost destroyed for good by Zordan's fleet but is saved in the nick of time by a surprise attack from Iona and Hyūga. However, her core is salvaged by I-402 and delivered to Yamato, who assigns her to infiltrate a human facility in a special mission with the promise of being allowed to return to Gunzō's side once it is accomplished. In the Ars Nova adaptation, Takao sacrifices her vessel self to save Gunzō and the critically damaged I-401. This results in a super submarine called the Ars Nova with the processing capabilities of both Takao and Iona. At the end of the anime she regains her Mental Model form.

Arpeggio of Blue Steel (蒼き鋼のアルペジオ Aoki Hagane no Arupejio) is a Japanese manga series produced by Ark Performance and serialized in Shōnen Gahosha's Young King Ours. Eight manga volumes have been released and an anime series by Studio Sanzigen aired from October 7, 2013 to December 23, 2013. The same studio is also producing two films based on the series to be released on 2015.