Hachi was named for the time of her birth- born precisely at 8:00 am according to the medical staff (as "hachi" is also the pronunciation for the number 8 in Japanese). Hachi's name is written with the katakana ハチ. It is worth noting that names written in hiragana or katakana do not hold specific meanings as names written in kanji do; they are purely phonetic.

While it's not uncommon for given names to be written in the phonetic-based katakana or hiragana rather than kanji, and while Hachi has no issue with the name or the set of characters selected on its own, it occasionally becomes a point of insecurity for her when contrasted to her sister Emi's name, which is written in kanji--specifically, the kanji 恵美 (恵 meaning "blessing, favour, benefit" and 美 meaning "beautiful, pretty").

For Emi's name to so deliberately note her as beautiful blessing while Hachi's name is much more simply based off of the time of her birth, well, it's prime fodder for (over?)thinking when Hachi gets caught up in trying to analyze it.