https://www.dlsite.com/maniax/work/=/product_id/RJ281588

text version : page 1 - 217
no text : page 218 - 428

i can only find the chinese translated version in this site, so here is the raw version

this is the remake version of author previous work with different ending
previous work have bad ending, while the remake actually have good ending (MC wins)

so if we want to order the series based on the original and the remake

part 1 original : /g/882370/d6581578d9/
part 2 original : /g/961854/a273129dd9/

and the remake version
part 1: you are here
part 2: /g/1686378/83aa2524af/
part 3: /g/1786548/5124afd9f3/ (END)

some SPOILER !
glad the author gives the remake mc actual brain and awareness about the heroine situation and not losing to the ntr guy usual attempt of blackmail .. well albeit a bit late but at least in part 3 all of the heroine is saved.
most of the mc works to uncover the ntr scheme is explained at part 3, while part 1 and part 2 is about ntr guy blackmail, drugging and corrupting mc girlfriend and his sister.
because the story have good ending, mc is able to the save his girlfriend and his sister before it is too late.

oh, and for those that want to see ntr guys wins ..
well there is an IF Ending from author fantia where the mc fail to save both his girlfriend and sister
i repeat its an IF Ending if you're troubled by that

i plan to also upload the IF ending as fast as possible so please wait a bit

IF/Alternate Ending : /g/1928041/e004e3d1b1/

Thank you so much for sharing this!

Base +8

Unfortunately, although there's an ending where he saved his sister and girlfriend, there are no scenes of him actually having sex with the girlfriend.

Base +6