A Simple Thinking About Blood Type (Korean: 혈액형에 관한 간단한 고찰; RR: Hyeoraekyeonge Gwanhan Gandanhan Gochal) is a South Korean 4-panel webtoon by art teacher Park Dong-sun (박동선) under the art name "Real Crazy Man".

The webtoon is themed around blood type personality classification and is serialized on Dong-sun's blog.

The webtoon has been published in book form and has been adapted into an anime series.

A Simple Thinking About Blood Type was first serialized on Dong-sun's blog as a webtoon.

[1] A short anime adaptation was made by Japanese production houses Assez Finaund Fabric and Feel in 2013, with a second season in January 2015.