So a few of you may be familiar with my idea for a story about Fuyumi and Tensei as a couple (if not it's visible on my page under the tags "#fuyumi todoroki" and "#tensei iida", if you are interested.) A significant part of the story revolves around Fuyumi being worried that Tensei doesn't love her, but the child they could make together (an unfounded fear, Tensei would prove). Why is this a fear? Well, let's take a look at the child herself.
Iida Kasumi (meaning 'mist') is the child of Todoroki Fuyumi and Iida Tensei. Her Uncle Shoto nicknamed her Steamed Rice Patty, due to her hair color (white) and her quirk (Steam Engine), as well as the meaning of the Iida family name. Her quirk, Steam Engine, is a combination of Tensei's engine and Fuyumi's unnamed ice-quirk+fire resistance. She has a set of 6 engines on her back in a slight v formation, with the wide ends just beneath her shoulder blades. While she isn't as fast as her uncle or her father (yet! She insists), she makes up for it with a far better boosting capability, thanks to her mother's quirk which both boosts her heat resistance and cools her engines more quickly. Her boosts are longer, and require less time between them. While she has never beaten Uncle Tenya in a short distance race, she's gotten close to tieing him in long distance races. Part of this is due to skating lessons from her uncle Shoto; it pairs well with her roller skates (also a gift from Shoto, much to Fuyumi's chagrin). Like her father and uncle, drinking certain liquids helps fuel her quirk. Water is the best, followed closely by mango juice. Her quirk is largely what Endeavor would have predicted, had anyone bothered to hear him out, and was thus the cause of Fuyumi's pre-marriage anxiety; though now days she can't believe she was worried; her husband is very caring to both her and their daughter.
Kasumi wants to become a hero like her uncles (she doesn't learn her dad had been a hero at one time until she's already part way through her first year, when they're learning recent hero history) and manages to secure a spot at U.A.'s recommendation exam thanks to both of her uncles. She makes it into the Hero Course (though who her homeroom teacher is I leave up to your imagination). Her favorite class, outside Heroics Training, is History, with the Rewind Hero, Stopwatch (Eri, who I couldn't think of a better hero name for). The reason it's her favorite is because she actually kearns a lot about her family history from it, which gives her a bit of insight into her parents (she understands why they don't speak of it, and she's glad they're letting her become a hero despite their own experiences either in the industry or with people related to the industry). For her part, Eri does try to skirt around topics which might be uncomfortable for Kasumi to learn (which doesn't stop Kasumi. She absolutely devours study material, a habit she picked up between her mother and her Uncle Tenya. She was a bit frightened by her research into Stain, and was in a funk for a while, until Deku (wow, the youngest number 1! Who was friends with BOTH of her uncles!) Told her about how he and her uncles had been the ones to defeat Stain (but that it was a secret and she could tell absolutely no one!)
This.... Got to be a lot longer than I planned. If you'd like to use Kasumi for a story, whether with her as a side character, or the main character, or even just mentioned, please do! I love when other people get use out of my ideas! And please, let me know!