Nami Hito was originally going to be the main heroine as her ordinary nature would balance out the eccentric nature of everyone around her. This was changed to making Kafuka the heroine as she had a better dynamic with Nozomu, being as deranged as he was but was outrageously optimistic in contrast to his persistent pessimism.
Nozomu Itoshiki's name is a Japanese pun. His name can be written vertically or horizontally, which provides an ironic meaning: written vertically it means "beloved hope", but written horizontally it reads "zetsubo", or "despair".
The series has an ambiguous setting, being a combination of the era the manga comic was being written (2005-2012, or specifically 2007, the time this series was created) and the Taisho Era (1912-1926). The anime enhances the retro setting with the use of early film visuals (title cards and a bleached monochrome look) and the use of katakana (old-fashioned Japanese calligraphy that is read vertically rather than horizontally).
Nozomu is in charge of Class 2-He. "He" is the sixth hiragana character in the Japanese iroha order, representing "6" or "F".