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The Battle of Heart and Land by MissKatt
Six years after Naraku's defeat, the Eastern lands have declared war on the West. Sesshoumaru's mother learns of the their numbers and, concerned, requests the help of Inuyasha and the gang. However, not all is right with Kagome and Inuyasha. (2011 4th Q. 1st pl. Best Action/Adventure&1st pl. Best Romance! 2012 1st Q. 1st pl. Best Dark/Horror! 2012 2nd Q. 1st pl. Best Drama! 2013 1st Bi-Annual. 2nd pl Best Angst!)
Rating: MA - Universe: Canon - Status: Complete - Category: Chapter Stories - Genre: Action, Angst, Dark, Drama, Romance - Updated: 12-08-15 - Created: 10-11-11 Chapters: 46 - Reviews: 535 - Words: 183,168 - Reads: 528,309 - Anonymous Reading: Yes
I didn't actually finish reading this fic – it got too angsty for me at a time when I couldn't deal with that much – but from what I did read, it might be what you're thinking of.
