Actually, she's also called Shioi. Origin is her being I401. Like Imuya(I168), Goya(58), Iku(I19). Just that she doesn't talk funny with any personal ending.

Demundo said:

Actually, she's also called Shioi. Origin is her being I401. Like Imuya(I168), Goya(58), Iku(I19). Just that she doesn't talk funny with any personal ending.

She's the only one with no weird verbal ticks or nicknames.
Weird is still a qualifier for the nicknames.

'Shioi' actually is a Japanese name (although, so is Imuya).

I noticed throughout the submarine grouping 401 usually left out

Curious and looked for their sizes. Lifting up Shioi seems impossible for the other girls, unlike the tiny Maru-yu

...well, Pacific is far bigger than the Atlantic and it's a long trip to the USA west coast ^^;;;

Oteck said:

I noticed throughout the submarine grouping 401 usually left out

She's the only submarine currently unobtainable thru standard means (construction/ normal map drops)

The Sen-Toku (the I-400 series) were considered as the largest non-nuclear powered submarine ever built. Also the IJN also has the fastest class of submarines ever built during World War 2, the Sen-Taka (I-201 series) having the speed of 15.75 knots when surfaced and 19 knots when submerged.

I-400, I-401, I-201 and I-203 were acquired by the US and expended as target ships so that the USSR won't acquire their technologies.