Toilet training successful again.

Since this week, Tetsushi starts to accept to do the toilet training again. We used potty as first. Two days ago, he suddently said "I sit" and we put him on the toilet. Then finally he could make pee successfully again in the toilet. When the weather is warmer, we will train him to make poo in the toilet as well. However, he still doesn't know how to tell us when he wants to make pee.