http://www.doujinshi.org/book/922283/

Base +47, hondawhr -24, observer1980 +21, mkspmk +6, Miles Edgeworth +48

DLsite - http://www.dlsite.com/books/work/=/product_id/BJ088719.html

DMM - http://book.dmm.co.jp/detail/b216afjm00500/

Artist HP - http://kumamichi.michikusa.jp
Pixiv - http://www.pixiv.net/member_illust.php?mode=medium&illust_id=57628600
Twitter - https://twitter.com/kumadano

Base +7, observer1980 +21

where is gender bender in this manga?

Base +6, DeltaX +8, observer1980 +21

gender bender on page 32

Base +6, asriel02 +6, observer1980 +21, Der Fuhrer +6

gender bender start at page 27

Base +6, observer1980 +21

What's the story of the gender bender?

Base +8

For the GB story: They're twins that share dreams, and in the dreams they can or do switch bodies for them. So it's implied in a past dream they wondered about the other gender. Then Rui has another dream where he explores Yui's body. Wakes up with an awkward boner and goes for fresh air where he runs into his sister. She reciprocates the curiosity and says they should continue where the dream left off. Rest is self-explanatory...

Base +6