After House Imagawa of the Daidoji was accused in 1170 of working with the Harriers they were invaded by rivals and their ancestral land, barrier islands off the southern Crane coast, was seized by rival houses.
The Daimyo of House Imagawa fell in combat and was replaced by his only son, he died and was replaced by his brother who likewise died as the summer war raged. They fought well but were hopelessly outnumbered by the other Houses.
At the end of the summer the leadership had passed to the youngest of 4 sons. He himself had only one son of gempukku age still at the dojo in Kyuden Kakita finishing his training, Imagawa Kira at age 15. He has a few more younger children from from 5-13. He apologized for his families support of the Harriers though he did not know whether it was true or merely a pretense to seize their lands, his seppuku cleansed the families honor and called off the war, they were left with one island with a few small fishing villages on it and a 15 year old daimyo who became a Samurai within a month of leading his house. A threat to nobody.
30 years later...
Imagawa Kira is an old man at 45 years old, the year 1200 is fast approaching as he calls his sons, daughters, nieces, nephews and skilled retainers to a council of war.
He looks across the table as waves crash over the beach behind him and the scent of smoking fish the island was known to produce. It took him 30 years to rebuild the families finances, 30 years to make House Imagawa worthy of the name, 30 years to plot revenge against it's enemies and a reclamation of it's former glory.
"I have waited a long time for this day. Too long some might say." he says, glancing at each of you in turn while he pauses. "It is not my generation that will be the future of the House," a pause. "It is yours!" Lord Kira slams his fist into the table to emphasize the word. "An opportunity has arisen, we go to war!" with the efficient speed of his Kakita training his wakizashi flies from it's spot at his side and plunges into the map he'd laid out at the table. "It is time to reclaim our honor."