He's likely 6'0 or 6'3, most of these shipgirls aren't that tall like NJ or FDG sadly *death by snu snu*
Wait, how tall is NJ anyway? She certainly looks the part, but knowing most artists, she's probably in a similar boat to Medusa from Fate, who's like 5'6" at most from what I recall (despite what her proportions suggest).
For anyone wondering, according to google the height of an average Japanese woman is 148.9cm, or 4'9" in imperial. So Akagi could very well just be short. For relevance the height of an average Japanese man is 160.3cm, or 5'2" in imperial