Foreword
All resemblances to names, organizations, events, etc. in this story is purely coincidental and does not represent any particular group or person dead or alive.
Regarding Japanese honorifics:
-san (さん): derived from sama (see below), is the most commonplace honorific, and is a title of respect typically used between equals of any age. Although the closest analog in English are the honorifics "Mr.", "Miss", or "Mrs.", -san is almost universally added to a person's name, "-san" can be used in both formal and informal contexts, and for either gender. Because it is the most common honorific, it is also the most often used to convert common nouns into proper ones, as seen below.
-sama (様 [さま]): is a markedly more respectful version of san and can be used for either gender. It is used mainly to refer to people much higher in rank than oneself, toward one's guests or customers (such as a sports venue announcer addressing members of the audience), and sometimes toward people one greatly admires
-kun (君[くん]): is used by persons of senior status in addressing or referring to those of junior status, or by anyone when addressing or referring to male children or male teenagers, or among male friends. It can also be used by females when addressing a male that they are emotionally attached to or have known for a long period of time. Although kun is generally used for boys, it is not a hard rule. For example, kun can be used to name a close personal friend or family member of any gender. Also, in business settings, young female employees may also be addressed as kun by older males of senior status. It can also be used by male teachers addressing their female students.
-chan (ちゃん): is a diminutive suffix; it expresses that the speaker finds a person endearing. In general, chan is used for babies, young children, grandparents and teenagers. It may also be used towards cute animals, lovers, close friends, any youthful woman, or between friends. Using chan with a superior's name is considered to be condescending and rude.
-senpai (先輩 [せんぱい]): used to address or refer to one's senior colleagues (lower rank black belts) in a school, dojo, or sports club. So at school, the students in higher grades than oneself are senpai.
-kōhai/kouhai (後輩 [こうはい]): is a junior, the reverse of senpai, but it is not normally used as an honorific; kun is used for this function instead.
-sensei (先生 [せんせい]: is used to refer to or address teachers, doctors, politicians, lawyers, and other authority figures. It is used to show respect to someone who has achieved a certain level of mastery in an art form or some other skill, and is also applied to novelists, poets, painters, and other artists.
In this regard expect the characters to speak Japanese despite the English text used.