DLC expanding on the story of Waffle swinging game: it covers the onsen trip of Tetsuya with Yukari and Mei, plus I believe some events of Yukari's past. Gallery for the original visual novel can be found here:
Was this game updated recently? I remember playing the standalone dlc some months back and it did not contain the scenes with Yukari's past.
Edit: I did some digging around on the official site and I believe they're actually two separate dlcs, as there are two different listings along with what seems to be a binaural function dlc.
Imma just post what happens in one of the DLCs. I played both but I only payed attention to the first one since I loved it way more. I didn't really pay attention to the DLC dealing with Yuakri's past so I don't actually know most of the details there. The first DLC (pages 39-74) takes place after the bad end of the main game where the MC's wife, Yukari, gets stolen from him without his knowledge. I say stolen but she never really was completely taken from him but he sure got that impression. It starts off with Yukari and Ai (I believe that was her name but I don't care much for her) going on a vacation to an inn with the Tetsuya (Ai's boyfriend). Its from Tetsuya's POV. Tetsuya basically managed to take both girls on a trip without the MC (how he did this, I don't know. It should be especially hard since by this point, the MC knows his wife has been cheating on him). He is both happy that he get's both girls, and kinda sad since he doesn't wish anything bad to the MC since they are best friends but his desire to take Yukari for himself wins over. Before they even get to the inn, he bangs them both in an alleyway and they're both in love with his dick. The moment they settle down in the inn, they get into the hotsprings with the intention or resuming where they left off in the alleyway. Tetsuya is of course happy with that and they get to banging immediately. The two girls decide to spice things up by saying they'll be Tetsuya's sex slaves for the duration of the trip and will pretty much do whatever he commands. After banging them in the hot spring, he proceeds to take Yukari's anal virginity. Furthermore, she swears that she'll only ever do anal for Tetsuya so he's basically one-upped the MC again. Finally he gets to banging them both one last time. Yukari points out that Tetsuya is trying to take her for himself to which he acknowledges. She gives him the go-ahead to try and he does. By the end, Yukari swears that she's Tetsuya's woman completely and that even if he gets married to Ai, she'll sill be fine as a side-woman. Tetsuya bangs them both some more and the DLC ends with him having pretty much conquered them both. Really wish we got to see how the MC took this news but it is what it is.
I've already replied to some of you individually through PMs. For the rest still interested in those DLCs, could you please check this link in the forum?