This page refers to the adult, Osomatsu-San version of Choromatsu. Click here for the Osomatsu-Kun version, where the Matsuno sextuplets are 10-year-old fifth graders instead of NEETs.Choromatsu Matsuno is the third son of the Matsuno sextuplets.
Similar to Canon!Matsu, he's brother who wants to reach his life goals. He desires to do more with his life than just being a NEET-- even if he is an idol chaser, it's just a hobby! From there, however, he diverts.
He's really shy, and still tries to be the most mature Matsuno sextuplet even if he gets shot down for it like he does in his script. Like his blue brother, he (tries) to live based on his script, mostly because it's who he truly is.
To learn more about the Osomatsu-San timeline, just watch the anime. There are around 25 canonical episodes, along with a few bonus ones, such as Episode 3.5, which you can find in the above link, along with Episode 26 (which has been rewritten under Osomatsu's request).