Yoshiyuki Terada

Terada-sensei, as he is addressed by all of his students, is a teacher at Tomoeda Elementary School. Through the fourth grade and part of the fifth-grade year, he is the homeroom teacher of Sakura Kinomoto and every other recurring elementary student character. Terada appears to teach a variety of subjects, including physical education.

As the series progresses, it is revealed that he is having a romantic relationship with his student Rika Sasaki. In the manga, they become engaged when he gives her a ring, noting that he hopes it will one day become her wedding ring. Rika gives him a teddy bear she made and named after herself, which legends says will allow them to remain in love forever. Towards the end of the series, the couple is shown having a picnic at a park, with Terada slipping away so Sakura doesn't notice him. During the series, none of the other characters appear to know about the relationship.
In the anime adaptation, their relationship is not shown in the same light. Their engagement and more romantic scenes between them are removed, and Rika notes that Terada reminds her of her absentee father. Terada is also shown accepting cakes made by Rika and in accepting the bear and naming it after his "hardest working student."

In the Cardcaptors English dub, he is simply called Mr. Terada, and all aspects of the romantic relationship between Terada and Rika are completely removed, with Rika's shyness and reactions to him made to appear to be more of a general fear of men than romantic feelings.
Source: Wikipedia.