DNA preparation methods were as follows: (A) DNA extraction by a simple “boiling” method, (B) DNA extraction by a “rinsing and boiling” method, (C) DNA extraction by a “protein fixation-1, rinsing and boiling” method, (D) DNA extraction by a “protein fixation-2, rinsing and boiling” method, and (E) No DNA extraction process. (A), (B), (C) and (D) were grouped into the “DNA extraction” method, while (E) was grouped into the “non-DNA-extraction” method. DNA polymerases tested in this study were TaKaRa Ex Taq™ and KOD FX Neo™.