and are an essential element of Japanese seniority-based status relationships, similar to the way that family and other relationships are decided based on age, with even twins being divided into elder and younger sibling. Senpai is roughly equivalent to the western concept of mentor

Mentorship

Mentorship refers to a personal developmental relationship in which a more experienced or more knowledgeable person helps a less experienced or less knowledgeable person....

, while kōhai is roughly equivalent to protégé, though they do not imply as strong a relationship as these words mean in the West. More simply, these may be translated as senior and junior, or as an elder compared with someone younger in the family/company/organization—the terms are used more widely than a true mentor/protege in the West. There is usually no average separation in age between a senpai and his or her kōhai.

A junior student will often refer to senior students as "senpai", and alumni

Alumnus

An alumnus , according to the American Heritage Dictionary, is "a graduate of a school, college, or university." An alumnus can also be a former member, employee, contributor or inmate as well as a former student. In addition, an alumna is "a female graduate or former student of a school, college,...

 will often refer to alumni from earlier classes as "senpai". This holds true particularly if events bring them together later on, such as joining the same company, serving on a board together, or simply being in a club or parent's organization at the same time.

On rare occasions, a younger person may also be considered the senpai of an elder person if circumstances dictate—such as if the elder entered an organization or company at a later time than the younger did.

Note that senpai is often seen romanized as "sempai" because it is pronounced that way (the Japanese "n" (ん) is pronounced as "m" when it comes before bilabials

Bilabial consonant

In phonetics, a bilabial consonant is a consonant articulated with both lips. The bilabial consonants identified by the International Phonetic Alphabet are:...

, such as "p").

Social roles

In a Japanese school sports club, such as a baseball team, the kōhai are usually expected to perform various menial tasks for the senpai including washing clothes and cleaning. The kōhai may not be allowed to play the sport at all or have only limited opportunities to do so until they become senpai.

More than simple seniority, senpai implies a relationship with reciprocal obligations, somewhat similar to a mentoring relationship. A kōhai is expected to respect and obey their senpai, and the senpai in turn must guide, protect, and teach their kōhai as best they can. Senpai/kōhai relationships generally last for as long as the two people concerned stay in contact, even if the original context in which the senpai was senior is no longer relevant.

In Japanese martial arts

Japanese martial arts

Japanese martial arts refers to the enormous variety of martial arts native to Japan. At least three Japanese terms are often used interchangeably with the English phrase "Japanese martial arts": , literally meaning "martial way", , which has no perfect translation but means something like science,...

, the term senpai generally refers to higher ranking students, some of whom may hold a black belt

Black belt (martial arts)

In martial arts, the black belt is a way to describe a graduate of a field where a practitioner's level is often marked by the color of the belt. The black belt is commonly the highest belt color used and denotes a degree of competence. It is often associated with a teaching grade though...

. They are expected to assist the sensei

Sensei

' is a Japanese word that basically means "person born before another." In general usage, it means "master" or "teacher," and the word is used as a title to refer to or address teachers, professors, professionals such as lawyers, CPA and doctors, politicians, clergymen, and other figures of authority...

 with younger or less experienced students.

These terms appear frequently in anime

Anime

is the Japanese abbreviated pronunciation of "animation". The definition sometimes changes depending on the context. In English-speaking countries, the term most commonly refers to Japanese animated cartoons....

 and manga

Manga

Manga is the Japanese word for "comics" and consists of comics and print cartoons . In the West, the term "manga" has been appropriated to refer specifically to comics created in Japan, or by Japanese authors, in the Japanese language and conforming to the style developed in Japan in the late 19th...

. Romantic crushes on one's senior are a popular theme in shōjo

Shojo

The term refers to manga marketed to a female audience roughly between the ages of 10-18. The name romanizes the Japanese 少女 , literally: "little female". Shōjo manga covers many subjects in a variety of narrative and graphic styles, from historical drama to science fiction — often with a strong...

and romantic stories. In translated anime and manga, senpai/kōhai are more commonly retained in fansub

Fansub

A fansub is a version of a foreign film or foreign television program which has been translated by fans and subtitled into a language other than that of the original.-History:...

s and scanlation

Scanlation

Scanlation is the scanning, translation and editing of a graphic novel from a foreign language into a different language. Scanlation is done as an amateur work and is nearly always done without express permission from the copyright holder. The word scanlation is a portmanteau of scan and translation...

s, as official translation

Translation

Translation is the communication of the meaning of a source-language text by means of an equivalent target-language text. Whereas interpreting undoubtedly antedates writing, translation began only after the appearance of written literature; there exist partial translations of the Sumerian Epic of...

s tend to use familiar English terms such as "upperclassman".