Am I the only one who still does not understand why he teared up the picture he made of Reina?
If you remember the scene where Kayano (main girl) remove the torn up drawing of Reina only to reveal another drawing. This drawing, however, was brighter and more cheerful (indicated by the use of yellow and warm color as opposed to the blue and cool tones used in the torn up picture). Reina was also smiling in this second drawing. I think this is symbolic and trying to show that Sensei had wanted to save Reina. He had wanted to bring back her smile and tear down/destroy the factors that had made Reina so withdrawn and afraid. I believe this scene and the two drawings served the purpose of revealing one of Sensei's end goals, which we might not know yet at that point in time. We're also reassured that Sensei is probably not a psycho terrorist who has a thing for his student. This is my guess as to the intention of the scene.
This is my guess as to the intention of the scene.