DMM/FANZA: https://www.dmm.co.jp/dc/doujin/-/detail/=/cid=d_227915/
DLsite: https://www.dlsite.com/maniax/work/=/product_id/RJ383240.html
Another extra doujinshi chapter to Hero no Himitsu (ヒーローの秘密) by Imamura Youkou (陽子今村) (yes, the romaji of the author's name is wrong on this cover), which can be found translated into English on MangaDex here: https://mangadex.org/title/b4a21b67-22e7-4482-add5-8cd9451bedfe/hero-no-himitsu
When I have time and money, I'll get this translated into English like the rest of the series.

wow,9 years ago first read it then read again

今夕是何年，上一次看原著还是在9年前

Base +7

哇，我高中的时候特地去找的漫画，好久了，估计2013、2014的时候，突然又看见了

Base +6

原作者亲自画的本子

Base +6

On page 22 you can see a reference to one of the author's other works and I tried to find it again but the only version I can find has the pages out of order and some of the pages are even messed up with like the bottom half of one page being pasted over by the top half of another page? What a shame.

Base +6

有谁看得懂剧情？想知道黄是什么情况

Base +6

黄和蓝不是男的吗？也性转了？

Base +6

外傳出二了!!
開始的那兩位,是不是上一代的啊?

Base +6