So I show how to make.
Pattern is on this page (I improved it a little).
Cutting.

Sew up the middle of the back from inside.

Sew sleeve (A to B) from outside. I used blanket stitch.
Sew the side (D to E).
Unsew B to C to D.

If you make boy's kimono, sew B to C and C to D. It is a rule. You may ignore.
Sew the collar to the bodice. Overlap 1 or 2 millimetres.

Obi is 1.5 × 32 centimetres. You may use a ribbon.
