The Ichigwa are a reptoid species who are very troublesome in the galaxy. Not because they do anything malicious, but rather because the're far too curious for their own good, which then leads them to create problems that many of the other races have to clean up. A textbook example of this is their creation of the Crassians.
One very distinguishing feature of the Ichigwa is that all of their ships are large, black cubes. Literally every ship is a cube, or very cubic. To them it is the most efficient ship design one could create. The Ichigwa are a species that is well known for their love of the geometric, especially cubes. Spheres, however, not so much, as they see rounded surfaces being wasteful of space. They are practicalists in roughly the same strip as the Gayik'Von, but are unlike their near cousins in the fact that they like things that are beautiful and decorative. Thus you will see things in their society that are more pleasing to the eye than you will with the Gayik'Von. Another big difference between them is that the Ichigwa hate wasting space. Hence the love of square shaped buildings, objects, etc.
So, while the inside may be elegant, the outside and base footprint/layout, will always do everything it can to maximize space and efficiency. Also, these are NOT BORG CUBES! So please stop asking!! lol. The Ichigwa just happen to like cubes, as they see it as a very efficient design. :) Ships of the design you see above can deploy smaller ships, such as shuttles and the like, for planetary recognizance missions, resource drops, specimen "acquisitions", and more. Also, not all Ichigwa shuttlecraft, despite their love of cubes, are cubes themselves. Some employ a clamshell design because, for the purpose for which they're deployed, it fits perfectly with the needs for which they were built.
Ichigwa ships also possess extremely good cloaking, which they *cough* borrowed from the Gayik'Von several millennia earlier (read: they flat out stole it) in order to make their efforts to collect specimens from other planets and species for study much easier. The Ichigwa are also a very pacifist culture, meaning that their ships are more focused on science rather than warfare. They can fight if they need to, but they generally prefer science over warfare, a trait that the Yandians like, while at the same time despising due to the unethical ways in which the Ichigwa gather, study, and then dispose of their "specimens". If an Ichigwa ship leaves their home republic, which consists of 3 solar systems and 8 inhabited planets, it is generally assumed they're likely going out to either acquire new subjects for study, or disposing of the latest batch which they no longer need.