but; although (emphasis)
Uses こそ to emphasize the preceding phrase while expressing a contrasting 'but' or 'although' nuance.
This pattern emphasizes the first clause to highlight an unexpected contrast. It often carries a tone of concession: "precisely because of X, but still..." or "even though X (which is extreme), ...". The が or けれど after こそ functions as a standard contrastive conjunction, but the こそ adds a strong focus on the preceding element, making the statement more emphatic and literary. It is common in written Japanese, speeches, and formal contexts, not in casual conversation. For example, saying 遅れてこそいますが... means "It is true that I am late, but..." with a nuance of admitting a fault while still making a point.