@7goat No, that's what I've been thinking, too. Takoha must be a descendant of Tsukihashi Yomiza. I wonder how Deido will take that.
It fits quite well, too. The year is 2017, so Takoha, just out of art college, must have been born in the late nineties. Assuming generational times of 20 years, this means his parents must have been born in the seventies; grandparents, in the fifties; great-grandparents, in the thirties, and great great grandparents in the teens. If we increase it to 25, we get Shinobu's approximate birth at the turn of the century as his great great grandmother, having a child around the time of WW1 when Deido (born 1904) was in middle school.
Also, this means Sei'ichi and Makoto, being Takoha's uncle and aunt, are likely also Shinobu's descendants and Deido's great-great-nephews.