First, there's Mr. Nino... He's the Korean teacher, but he makes spelling mistakes all the time.

Second is Mr. Robo. He's very stiff. Of course, he's only stiff on the outside and is actually quite caring deep down. But usually, he just seems way too indifferent.

Third, Mr. Otto... He has 'incredible' English skills. He has a legendary record of pronouncing 'museum' as 'mu-se-um'.

Fourth is Mr. Iro. There's nothing particularly wrong with him, but he jokes around way too much except during experiments. He loves games so much that he sometimes plays them instead of teaching.