
Have you ever wondered why Japanese never put "sensei" as their titles? Here is a bit of cultural information. Sensei can be a job title of being a teacher but the characters used for sensei literally mean "born before hand". So if someone has skills or knowledge that that seems to have a longer history or depth than others, then people may choose to call the person "sensei" as a matter of respect and desire to learn things from that person.
So it is often a position being offered by others, not oneself. A sensei should ideally be humble, so it is weird to describe themselves by saying "I am more knowledgeable than others". Of course, if someone asks what they do, they may say "I am a teacher" but until being asked, Japanese don't call themselves or write Sensei beside their names.
In name cards, Japanese may write Kyoshi, Renshi, Hanshi or Shihan beside their names as these are earned ranks and you often have to pay an association for these titles—just like a university degree. But Sensei is not always a rank or paid title. Ideally speaking, one is either just being a sensei or not a sensei.
Also, Japanese may use Shihan (meaning exemplary teacher or a master) on their name cards, but they will never say "Call me Shihan". Once again, that appears not very humble and it is up to others to decide. Unless they are very senior or there are many teachers and there is a need to identify one specific teacher, most people generally prefer just using the word Sensei.
Courtesy Natsuko Minegishi