Part of why I designed my characters the way I did is definitely me thinking "hey, this looks nice!", but there's more to it than that, definitely!
Masahiro and Akane - like a whole bunch of other characters in Grassblades - are designed as a pair. There are some elements between them that match (hair and skintone, the beige and red colours in their clothes, etc.), but there are also a lot of elements intended to contrast.
Masahiro is one of the tallest characters in the comic, while Akane is definitely the shortest. Masahiro's got ragged, multilayered clothing with lots of detail - Akane's got a simpler outfit. Their body-language is different, etc.
But like I said, a lot of other characters are designed in pairs - or groups. Some elements matching, others contrasting, so that when they show up in the comic, it's easy for the reader to tell individual characters apart, but also to recognise that they kind of belong together in a story-context. I also put a lot of work into the colour-scheme and costume design for various groups of characters - the guards of noble houses all wear unified colour schemes and similar clothing, for example. Masahiro's got that big coat of his both to hide in, and because it lets me emphasise motion when he's in the middle of a fight.
Well, in the case of Masahiro, I decided to go with a male character since the main relationship he has to deal with is the parent-child dynamic he has with Akane - and too many times female characters end up taking on the parental role, and I wanted to sidestep that. It's also partly due to the inspirations for the comic being a lot of wandering-men-and-small-children stories (Lone Wolf and Cub, some parts of Usagi Yojimbo, etc.)
In terms of the genders of a lot of the other characters... A lot of people in positions or authority in Grassblades are women. You've got ladies of noble houses, you've got captains of the guard, etc. This is very much intentional. Having grown up in a pop-cultural landscape where all-male casts are seen as normal and unremarkable, but casts that are majority-female are somehow still odd, I decided early on that the world of Grassblades would be one where men and women were equal, and where women in positions of authority could have that authority without being questioned. I don't talk about it within the story - no character ever remarks on the presence of women and their equal rights - it's just sort of there.
I also try to include a wide range of skincolours and body-types, because it's just more interesting to draw. I've got a couple of characters that people have actually mistaken the gender of, because they aren't overtly gendered; Kazue, for example, gets mistaken for a man a lot, because she's very flatchested and doesn't have much in the way of curvy hips either.
Because I didn't want to tell a coming-of-age story. 99% of the cast of Grassblades are adults. Akane is the only child with a prominent role (not counting minor bit-part characters), and there are no teenagers in the main cast. Everyone is in their 20s or older.
Masahiro is somewhere in his mid-thirties - a ragged, tired mid-thirties - because I wanted him to have a lot of space in his history for stuff to have happened so that I could explore it later.
... Also, it is a lot more narratively interesting to me to take an adult character, who should by rights be settled into some sort of stability and have finished the most dramatic growing of their life, and then shake them up a whole lot and see what falls out.
Well, Akane's parents are found dead from a bandit attack on page four! XD There's a point to that - she needs a reason to attach herself to Masahiro's leg and refuse to let go - but that's the only dead-parent thing that is brought up within the narrative, I think.
