Luke and Jan Valentine's Merry Manga

Luke and Jan Valentine's Merry Manga (ルークとヤンのあとがきまんが,) is an omake of the Hellsing manga, not appearing until Volume 2 of the manga.

It's a very short, fun afterword which stars the Valentine brothers, Luke and Jan. Appearing at the end of the volumes, every volume has Luke and Jan talking about different stuff. It's also not in-universe, meaning that Luke and Jan are basically self-inserts. They talk about things like Gundam characters, making fun of the pacing of Hirano himself, etc. Essentially, it's just Hirano having fun; as the drawings are messy.

They are also Kouta Hirano's favorite characters, which would make sense as to why he would make an omake manga specifically for them.

Trivia

 * Volume 5 is the only time that Luke and Jan's names are switched around in the title of the Merry Manga.
 * In the afterword of Volume 3 of Hirano's next manga after Hellsing, Drifters, Jan and Luke appear. They're also the main characters of the specific afterword, and the afterword is titled "Luke n Jan''s Arma-Goddamn Corner."