If you read the story closely enough, you would've realized that Sawaragi didn't use Shin to smuggle drugs at all. He purposely hid a drug packet in the coffee that he handed Izumi to protect Izumi when in reality, they were just normal coffee beans.
http://www.mangago.zone/read-manga/takaga_koidaro/an/takaga-koidaro-chapter-5.html/13/
Also, being angry isn't an excuse to almost rape someone - there is no excuse for it... and it's still considered rape, even if they didn't go all the way. I don't hate Shin, but he made a ton of stupid mistakes, and I don't hate Sawaragi either - other than being in the yakuza, his biggest crime is taking advantage of Izumi's pain (he liked Izumi before his sister died, and he was also very hurt, it was a combination of things) even though Izumi didn't see it as being taken advantage of.
About Japan and asian countries not being open and accepting about gay community is false. Religion one of the main historical cultural reason for the bashing and alienation of LGBT, and Christianity is an example of it. Several writers have noted the strong historical tradition of open bisexuality and homosexuality among male Buddhist institutions in Japan.
For more info on the subject:
http://www.slate.com/blogs/quora/2015/05/28/how_does_japan_treat_gay_people.html
https://pairedlife.com/dating/Being-Gay-in-Japan
I really enjoyed this. I love makoto and the fact that he is the ultimate cock block. And I know a lot of people hate Shin and in a way I understand where they're coming from, but I like Shin. It could be just because I understand him a bit because I'm just as awkward of not more awkward when it comes to having a crush. Also you have to keep in mind that in Japan, most of Asia for that matter, being gay isnt as widely accepted as it is in other parts of the world. Plus, Shin was young when he hurt Izumi. Taking all that into account, I DON'T hate Shin. He was just afraid and confused by his own feelings, just like how I am in the fact that I also have a crush on one of my best friends and it took me forever to even realize that I wasn't thinking of him as just a friend. And yes he does know But he just wants to be friends
So I understand why Shin said what he did to Izumi in middle school. He was afraid of destroying his friendship. Sawaragi on the other hand. I hate that guy. He took advantage of his just recently deceased sister's husband (like not even 24 hours) while Izumi was drunk out of his mind and mourning. He used the man he supposedly loved to traffic drugs for his own benefit, knowing it could get Izumi arrested leaving Makoto (his ONLY nephew) an orphan without even understanding the circumstances. He purposely angered Shin which caused him to go and practically rape Izumi. I just over all did not like him. Still a good story though. Okay I'm done ranting. Would like a story of Makoto and Ai though