(Akari's page was getting kinda long, and this stuff is never updated, so....)
Akari was born shortly after Shizumaru was finally released from prison, and he and Rimururu decided to make a new start to family life. Akari has always been a very happy person, although there's an air of...something odd about her. Most notably, she is very attuned to souls and spirits. She saw dead people when she was young, and still sees them now that she's grown up, as she's studied spirits a lot in conjunction with her sorcery. She's quite good at summoning up spirits and demons to attack her enemies, or have a tea party, if she so desires. She's also pretty good at exorcisms.
This has earned her some notoriety, naturally. Some people do not view this favorably at all, but others have flocked to her wishing to hear from their dearly departed. While at Ohtori, this got her dragged into one of the occult societies/student groups there, which she grudgingly stayed in touch with even after she graduated and entered the Great School of Magic in Lemuria. She is now also part of a paranormal investigations group, having joined several years ago, figuring that it's a good way to make some practical use of her abilities.
(Note that these demons and such are not the sinister creations of Western mythologies, but more like the ones that Akari uses in Last Blade-- Japanese in basis, kinda silly sorts. The spirits of the dead, she doesn't usually actively seek out and bother, because that's rude. However, those that linger around have a tendency to find her and talk to her.)
The other odd thing is that...she likes to stay in a 13 year old body. Once she learned shapeshifting, that's the form she's stayed in most of the time. When questioned why, she says that being too grown up is boring. She likes to romp about in this form, and eat candy, and play with puppies, and.... (She has quite a sweet tooth, which is why she managed to score one of the rare Golden Tickets for Wonkaland--the odds were in her favor.) She also tries to get other people to have fun, though she does understand that different people have different ideas of fun.
Another notable aspect to her character is her general disdain and apathy toward romance. Some speculate that she got her heart broken somewhere, sometime, and this is the result. (She refuses to confirm or deny this.) One of her well-known sayings is, "Eh, romance is a crock." And she also seems to have an absolute lack of interest in sex. Not in a prudish, ew ew ew get away from me kind of way, but vaguely amused (or maybe disgusted) by the lengths some people will go to get it and otherwise not caring about it. If pressed, she says that she doesn't approve of the group marriages (both the Chaos foursome and the ruling family of Arcadia) and such, something no doubt picked up from her parents, who are relatively conservative on such issues.
Now, people seriously hitting on her or trying to get into her pants (one would hope her grown-up form, of course; possibly one of the reasons for her child form is to discourage such things--although it has the downside of being a draw for much less savory types...) will find some up-front hostility. On the few occasions that she actually answered the question rather than sicced an army of macarena- dancing paper dolls on the asker while laughing maniacally, she has said that she's still a virgin.
Despite her childish facets, she does have some very grownup qualities. She is very diligent in her studies of sorcery and spiritualism, and has become quite accomplished in those fields--particularly in the combination of them. And when she does need to be taken seriously, she can assume a very professional, businesslike demeanor, usually shifting into her natural adult form for that.
At times like these, it's easier to see that she does have a sense of responsibility and duty. For instance, she served with the Forestals quite commendably for some time, and received excellent marks while she studied at the Great School of Magic in Lemuria. There's also a rumor that she spent quite a while in fasttime out in Shadow, during the year she left Amber, fighting in some sort of mentalist war. She doesn't like talking about it, though.
The one time she was genuinely scary in front of many witnesses was during the tail end of the Viking Wars, in one of the last gasps by the Vikings. During this raid, one of Akari's friends Achi was badly injured and almost killed. This drove her into a fury, and she summoned up more demons and spirits of the dead at once than just about anyone had ever seen before to attack the raiders, who were wiped out. (The fact that she was so enraged that she didn't think to change into her adult form probably only made it all the more unnerving, to see a livid 13 year old girl unleashing hordes of spirits on her enemies. Of course, she then broke down and cried like a baby at Achi's side afterward.) This became known as the March of the Dead, or the Hundred Demon Sabbath, one of her most fearsome spells. She then accompanied her father on the next strike on the Vikings' home shadow and repeated this to help with the eradication effort.
She's very easygoing, naturally, with the one hangup about relationships and sex. Hitting on her, trying to get her set up with someone, that can get her a bit peeved. Generally, she's open and friendly and tries to get people to have fun. She is very close to her parents, of course, and some other members of the family. Nanami Major, Nausicaa, Makoto, just about the entire Harad branch....
There's one notable exception to her happy, carefree interactions, and that would be the group marriage in Chaos. Those times that she has been around them, she has become seemingly uncomfortable--physically uncomfortable--for some reason, and generally avoids them as a result. She insists she doesn't know why this happens. She tries to be polite and her usual cheerful self, but it's pretty clear she'd rather be somewhere else. Akari doesn't like to talk about them much, though it does seem like she vaguely dislikes them--probably because of that strange reaction.
As mentioned earlier, she also disapproves of the Arcadia group marriage, but doesn't seem to react negatively to them as people, either physically or socially. She is pretty good friends with Random.
She's known to hate Bust Rimururu, or as she calls her, Mommy's Evil Twin. This carries over (to an extent) to people who associate with the Primal Whore. This is assumed to be part of the reason she dislikes Orien.
Akari is known to think of her deceased brother Moriya very fondly; it is probably because of his memory, in addition to her father's role as Child of Wood, that she went to serve as a Forestal, and studied some of the lore of wood as well. Interestingly, he is apparently not one of the spirits of the dead that she has ever been able to speak to. Yet, this does not seem to trouble her; if asked about it, she simply shrugs and smiles a bit oddly.
In recent months (shortly before the start of the game), she has seemed generally preoccupied and somewhat more subdued than normal, though not overly so.