Koinosuke is an inane 300
year-old assistant to Yagyu
Jubei. It was his job to find
the successor of Yagyu Jubei and
the new owner of the lovely
eye-patch. So after 300 years of
trial and error, he finally
finds Jiyu. He then takes up
residence at the Nanohana house
and builds "Koinosuke's Hut" (a
Dog House) outside the house to
live in.
 
Although his social skills
aren't great, he tries to fit in
to the present culture. He also
cares deeply about Jiyu, but his
obsession with the eye-patch
sometimes gets in the way. His
intentions are good, but he
constantly nags Jiyu about
carrying the eye-patch and
always tries to convince her
that she's Jubei II. His life
centers around the mission he
was given by his former master
and he struggles to find a new
life after he finds Jiyu.