The Mogami hadn't been doing too well since the beginning, when their first settler sought the friendship of a nearby village but instead found that it was full of barbarians. This setback left them in an inferior position compared with their more powerful neighbors, the Date and the Uesugi. Date Masamune was in fact Mogami Yoshiaki's nephew, but relations between the two clans were soured when Date refused to give the respectful bow to his elder--he had reasoned that it was unnecessary to do so for a daimyo who controlled a much smaller domain. Later Date was said to have discovered his mother (also Mogami's sister) putting poison in his tea, whereupon he swore revenge and declared war.
Mogami did not take the insult lightly. But when the Date soldiers surrounded his castle, he would not suffer the shame of surrendering to his own nephew and instead chose to commit seppuku, with many of his loyal supporters following suit.
But while Date Masamune managed to escape death by poisoned tea, he himself would ultimate succumb to another drink. Many jugs of sake had been ordered for his victory celebration, to which he invited all the brave warriors who had fought under him. During the feast the daimyo emptied a few too many goblets and began stumbling around the courtyard, drunkenly muttering verses of some forgotten poet while colliding with other revelers. Little did he know that also present at the feast were a handful of ronin who felt quite scornful of this fratricidal behavior, so he was in for a rude awakening when he approached and attempted to fondle a beautiful geisha, only to find himself impaled upon a hidden dagger.
Ordinarily this would not have been a mortal wound, but Date had lost control of his senses for a while now and simply laughed the matter off while continuing on his romp, though limping a bit more noticeably. Two attendants eventually carried him off to his private quarters, well he fell sound asleep, never to wake again. This blade, as it turned out, was poisoned too.
And like the poison spreading through his body, the lawless hordes of the ronin spread across the land that was once under the rule of the Date.
Meanwhile, the ronin of southern Honshu had at last converged upon Osaka, where Matsunaga Hisahide was plotting his next move in the race to occupy the lands vacated by the Mori and Urakami. So far it was the Chosokabe who had been most successful in building settlements on the other side of the inland sea, while the Oda and Saito clans were also extending their reach westward. Matsunaga wondered why the ronin weren't attacking these other targets that were much more vulnerable, but it was only after a kunai had lodged itself in his throat that he realized their objective was to assassinate the daimyos, not to plunder the villages.
And thus the Matsunaga clan was wiped off the map.
During this time, Tokugawa Ieyasu had steered clear of conflict with his neighbors and instead devoted his efforts to studying literature and poetry. He gathered all the books and scrolls he could from all over Japan and expanded his archives to house a Great Library, which he opened up to the public. This would serve only to increase the technological advantage he already held over his rivals.
Chosokabe Motochika had been building a library of his own, but upon hearing that the Tokugawa had completed theirs he shifted his interests to drama, and converted the structure to a hall for Kabuki performances. He wouldn't be able to catch up with the level of sophistication demonstrated by the other Sengoku powers, but at least he could always be entertained.
All that he had to worry about was his arch-nemesis on Shikoku, Ichijo Kanesada, whom he would have to eliminate as soon as the opportunity presented itself. Then he would be secure at last... or so he thought.