Fixed handle (kotehan)
Overview
A fixed handle (kotehan) refers to a person who posts on an anonymous message board using the same handle (nickname) every time. The term has been used on anonymous message boards such as 2channel. On anonymous boards, the default is to post as Nanashi-san ("no-name"), but some people chose to keep a fixed name.
A fixed handle sits between anonymity and using your real name. You don't reveal your real name, but people can tell it's the same person. This "semi-anonymous" state leads to a unique kind of communication.
The "invisible fixed handle" in a question box
In a question box, the sender's name isn't shown. Even so, the person answering sometimes notices from the writing style or content that "this question is from the usual person." The clues are a distinctive turn of phrase, questions in the same genre every time, and a unique way of using emoji.
This "invisible fixed handle" can also add warmth to a question box. Some people answering feel "they came back again." Regular senders are part of a question box's community.
Personality within anonymity
Even when they are completely anonymous, people find it hard to erase their personality. The length of their messages, how they use punctuation, the angle of their questions, and the words they choose combine, and "what makes that person who they are" can show even within anonymity.
As a sender, if you want to protect your anonymity, one way is to change your writing style on purpose. But whether to go that far to protect your anonymity is up to the sender. Being noticed by the person answering as "the usual person" doesn't necessarily lead to a bad result. If anything, it can be read as a sign that a relationship of trust has been built while you stay anonymous.