Round 1 Yaegashi is jabbing and giving Sosa a wide berth, tracking left and right in semicircles around him and then darting in with quick teardrop 1-2s. Sosa is sticking the jab out, getting a sense of aim, then fires a hard right cross and grazes the bridge of the nose as Yaegashi pulls his head back and moves his feet. Sosa is leading with the right hand now, falling short as Yaegashi moves quickly outside and turns off the ropes. 10-9 Yaegashi, close but the challenger while the aggressor didn't get to land very much.
Round 2 Yaegashi is staying beyond the reach of Sosa's jab, pushing off the balls of his feet to circle with his stance fixed shoulder-width. Yaegashi darts in and out with jabs, eluding the 1-2 with lateral movement and jumps outside as Sosa tries to time him with it. Yaegashi is giving Sosa's power lots of respect. Sosa is following, missing right hand leads and jabs lunging out at Yaegashi. Lots of directional changes by Yaegashi, making Sosa trip up a bit crossing his ankles. Side to side, in and out by Yaegashi. Light midair 1-2-1-2 by Yaegashi soaring in, quickly leaping away while Sosa fires a hard 1-2 of his own. 10-9 Yaegashi 20-18 Yaegashi
This is so far not developing into the expected war (though it might if Sosa gets his way), but is a pleasantly surprising chess match.
Round 3 Yaegashi is circling and tossing jabs now over Sosa's head. Chopping right hand and left hook by Yaegashi. Very low approach by Sosa, putting in overhand leads and left hooks on the chest rather than stick with the ineffective 1-2. Yaegashi is getting tagged now, Sosa's adjustments proving very successful. Hooking exchange and Sosa gets the best of it. Yaegashi got clipped hard a few times and knees buckled, still throwing back and scoring with his own hook-right-hook combos and maintaining his footing. 10-9 Sosa, just edging it with the more effective blows IMO (though Yaegashi got in plenty) 29-28 Yaegashi
Round 4 Yaegashi is hopping around Sosa, far out in orbit, drawing him into the ropes and landing double jabs and sneaking the looping right in past Sosa's left glove to crash into his cheek. Sosa is patiently walking Yaegashi down, looking to find him with a 1-2 up top or some lunging but economical body punches, not wasting anything. Yaegashi keeps to the ropes, in constant motion, countering Sosa after making him miss (for the most part). Long right hand by Sosa grazes as Yaegashi is pulling back into the ropes. 10-9 Yaegashi 39-37 Yaegashi
Round 5 Yaegashi is crouching in wait, and launching huge straight rights into Sosa's face as he creeps his way inside. Sosa is doing nothing incautiously but Yaegashi is clever enough to lure him into traps anyway. Yaegashi is leading Sosa around the ring and catching high overhand rights on his left forearm, quickly flinging it upward as needed to shield his face and circling to his right to line up a counter right hand. Yaegashi is jabbing the body from outside and then darting away. Long 1-2 by Yaegashi, ducked. Big overhand right by Sosa falling short. Right hand to the body diving in by Sosa, coming upright with a hook just as Yaegashi hooks in turn. Jab by Yaegashi. 10-9 Yaegashi
Sosa's gonna really have to go for it now, but I just think Yaegashi movement's too much for him. I can see it being a near shutout if Sosa can't close him down.