The personality of Arikawa is endearing, it makes having to put up with Sonya's klutziness more bearable. But the story finishes strangely as if the author's intention changed very drastically around the climax. One by one, the antagonists are introduced, promising a fierceful encounter, but ended up either being defeated without the protagonist knowing (e.g. the guy with the World Peace talisman) or not having chance for a second duel (the Shichiten-Hakki woman). The only encounter which had a good build-up to finishing was with the first academic-excel boy and the business guy with the Kansai maid.
At least the ending was touching. It was awkward though, it never revealed that Sonia was under some curse, instead it just showed Arikawa's selflessness.
This story could have fared better if it was more lengthy. Judging from the first battle (academic showdown), and the other one (money can't buy everything showdown), I think the author has a potential in making good stories. This one probably ended due to some unavoidable circumstances, who knows...