Boichi often makes crossover or cameo in his manga, did you notice the?
In level 1 page 9 we can find several picture’s over the walls and door of Ken’s room that are real work by Boichi.
The poster on the walls of the Sun Ken Rock team’s office has lots of poster. Here’s a few I was able to find. From Left to Righ.
What about the cross over with Space Chef Caisar on p12 of level 34? We learn that Ju-Mon Caesar from Sun Ken Rock is in fact the ancestor of Caisar from Space Chef Caisar!!!
Boichi is a fan of Trigun by Yasuhiro Nightow and so for the release of the movie “Trigun : Badlands Rumble” (24 april 2010), Boichi published a special 32 page long chapter called “Trigun – The Lost Plant” in Young King #10 from Shônen-Gahôsha. What’s more he advertised the movie in theatre with that chapter.
level 68 page 18: SM on the wall
level 68 page 19: SM on the wall
page 5 of level 80: main character of Diablo Metatron, another manwha by Boichi.
In the 21st page of the fist chapter we can the scene where Ken gets rejected by Yumin in Sun Ken Rock level 1