Your fault then
We only took a short trip to Sendai at the end of our holiday. Just 1,5 days before we went back to Tokyo and then back home.
We went to
Rinnō-ji, which has a really pretty little garden. The weather was kind of meh, and many of the plants looked like they were already past their prime for this season, but it was still a lovely place. We also went to
Matsushima that day, and I would really recommend doing that when the weather is nice

it was quite rainy and cold when we went there, and once the sun started to set, it got a bit uncomfortable. It's at the seaside, so this was kind of to be expected. Still, not a waste at all, we spent some time strolling over the islands, and that was actually fun.
From
Aoba Castle you have a great view over the city. On that day the weather was a little nicer to us. Many clouds, but the blue of the sky was unreal. I spent most of my time there just checking out the view.
Zuihōden Mausoleum was awesome, too. The monuments look great and the surrounding area is drop-dead gorgeous. You have to walk up like a gazillion stairs (then again, when don't you in Japan?), but the grounds are so pretty, and you are way too busy looking around to notice that you have to climb Everest. We also went to
Ōsaki Hachimangū, where we went up another billion steps............