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Eh I wouldn't necessarily call it harem. As you already know Grid has a wife in the game(Irene) but he ends up getting irl relationship with someone. The relationships is honestly barely mentioned and interferes with the story in no way. To me it seemed like the author had Grid enter a relationship in order to contribute to his character development.
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Irene isn't mentioned that often but his wife in the game is an NPC. She is very kind and understanding. A little bit of a spoiler would be that through a series of circumstances she gains 'Divinity' and she also learns swordsmanship. I'm assuming she isn't that strong but at least strong enough to defend herself.
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No. In total it is 3. One NPC and 2 players. He is married to Irene in the game (the NPC) and he is in a irl relationship with Yura. The other player is Jishuka but he obviously turns her down for Yura however he likes both of them. Also I see you responded to someone else's comment about Grid and Irene having a kid. Yes that's true and think of their kid as someone with the potential to become the strongest.
Ya'll is this a harem?? Cause I saw from the novel that it has the harem genre but I'm still asking anyway cause maybe the manhwa isn't going to follow the novel