The personification of the Type IXC U-boat of Nazi Germany's Kriegsmarine during World War II before she was sold to the Imperial Japanese Navy and became RO-500.
She is overall very pale, expressionless, and has long light blonde hair and blue eyes. She wears a garrison cap with dog ear-like protrusions coming from the back of it, a cropped jacket with a black dress and what could be either black pantyhose or thighhighs with bike shorts.
For Summer 2017, she obtained a seasonal CG which is shared to some level with her RO-500 form. She wears a white school swimsuit labeled "U-511" where it is labeled "RO-500" for her "future" self. She also wears a heavy dark blue jacket over her swimsuit along with her usual hat. You can clearly see that she has tanned (but not to the same extent as RO-500). Again, like her "future" self, she wears a blue bow where there would be a flower at the same spot. She is eating some ice cream. Damaging her simply gives her a brain freeze.
She speaks in a soft, quiet voice. She mentions in lines about how she is getting used to Japanese culture and the Japanese language. She is frequently depicted with I-58, who teaches her about Japan or shows her the ropes of being a submarine in the IJN (i.e. Orel cruising).
