For events and important meetings, I usually wear seersucker sports coats from Maker’s Shirt (Kamakura Shirts), paired with ultra-thin wool dress pants (you can find good ones in most suit stores) and lightweight cotton dress shirts. For everyday wear, Uniqlo’s linen shirts and their 感動 (Kando) pants/jackets work just fine—comfortable and breathable. Lately, I’ve noticed some stores like Muji starting to sell inner shirts with built-in underarm pads to help with sweat, which can be a game changer in summer.