I wonder if the sweetheart Seiroku was talking about is Noriko, after all, and if Kengo married her partly to prevent her betrothal to Yosuke, who went for Inako in turn, and that’s why Noriko helps Inako in every possible way.

Ah, Kengo blaming himself for something out of his control, a classic. Kihachi took it as a champ, though. Thanks to Inako Kihachi’s even started to believe in Seiroku’s confidence in his little brother’s inventiveness to the point of letting go of the electrical catalog.

However, I don’t think Yosuke even cares about the promise between him and Seiroku of bringing electricity into the world anymore. Seems like his only goal is to bring Seiroku’s doll(s) to life with electricity.