Honorifics are the suffixes and titles attached to names in Japanese, such as -san, -kun, -chan, and -sama, which encode respect, closeness, age, and status. They carry social information that English mostly leaves to tone.
Japanese packages a social map into its name suffixes. -San is the neutral default of respect, -kun leans toward boys and juniors, -chan toward children and the dear, -sama raises the respect to reverence, and -sensei marks a teacher or master of a craft, with dozens more in the wings. Dropping a suffix entirely, yobisute, is its own statement, of closeness or contempt, and characters hear it instantly.
This makes honorifics a genuine translation problem rather than a decoration. A relationship's whole temperature can turn on a suffix change, a scene's meaning can ride on a first name finally used, and subtitles must either keep the suffixes, as many official releases now do, or rebuild the signal in English. Dubs usually rebuild; subs often keep.
For factual work the rule is version discipline. If a quiz turns on how a character addresses another, the release being tested must be named, because the honorific may exist in one version and not the other. The glossary keeps the vocabulary; the canon sheet keeps the versions straight.
In use"When she finally drops the -senpai and uses his first name alone, the whole audience hears the relationship move."