IsekaiWriter

Mr. Tall elf refers to the protagonist ('s illusions) using she/he depending on the illusion's gender, but canonically, he's not speaking English. In his language, which is better than English, he's using a gender neutral term since he knows Protagonist is a plant. I, the "translator," could have used the term "they" but that would have felt clunky. Also, the protagonist's gender before they were reincarnated was never specified. This is to leave the character more open to interpretation. 

POV: Tall elf

After giving the potted grass a thorough scolding for scaring the shit out of me, one of my neighbors came inside and asked me if I was ok. Embarrassed I frantically explained the telekinetic grass on my table had pulled a prank on me and I was angry at it. "You're so silly, Orrian." After she left I turned back to the potted plant, which had not reacted to my verbal assault whatsoever. The girl appeared on the stool again, and leaned on the table, eyeing it as if she might fall through. Then her elbows started clipping through it. I suppose illusion magic is hard. She started spewing more gibberish, slower this time. Each sound was pronounced, and everything was clearly intentional, but I had no idea what she was saying. She got off the stool and started walking around the table, but it was jarring to watch. Our plant clearly didn't know how to make illusions walk right since her feet seemed to move with her as she bobbed around. I decided that since she clearly had no intentions, I would proceed with my day as normal.

It's been two months since then. The girl appears every-time I enter the house, though it's really just my office, since the bed in there is just for naps. I sleep in my wife's home. When other people come in, they can't see her until she notices them. This scared the absolute bejeebles out of my wife the first time she came in. She appraised our plant and confirmed it was casting the illusions, but she had never heard of the skill it had. At some point in the plant also got a skill that's supposed to help with learning languages, but so far she's only ever uttered short phrases to me. The scariest thing she does it take forms other than a little girl. There was a straight week where every time I closed my eyes she would shape-shift into something else, whether it be my mother, my wife, a butler, a human man, a monster, a horse, a bigger plant, or even me. One time she followed me outside but only half of the people there could see her and I guess she ran out of mana because she disappeared, clairvoyant eye and all. She's also learned to pick up objects with telekinesis and make it look like her illusion is holding them. The only way to tell she's not a real elf girl is to touch her or to look too closely at her shadow, which just looks wrong somehow.

She always plays pranks on me. Rearranging my paperwork when I'm not looking, stealing my pens, and moving furniture around constantly. She seems like a very mischievous person, or just very bored.

I'm reading a book and the plant, who I've nicknamed Briar, is watching over my shoulder, making notes on her papers, presume-ably with the words she sees that she doesn't know. She always does this. "Bench?" "For sitting, made from wood." "Penalty?" "Punishment for doing bad things." "Love?" She always asks that one. I'm sure she knows by now what love is, but she continues to ask it purely because she knows it's hard for me to answer. "Fuck off." She giggles, like she always does.

POV: Briar

It's been six months since I got the illusions skill. I've been studying hard to learn the language here, and even picked up a skill that helps you learn languages by trying for it whenever Orrian wasn't around. He's told me many things since I became fluent in the language about a month ago. First, this world has 3 continents. Iceland, Greenland, and Theguya, which is where we are and the largest. Iceland and Greenland aren't actually called those, but those are what their names really do mean. Just like the ones on Earth, Iceland is a really nice place and Greenland is a very cold hell-hole filled with ice monsters and ferocious penguins. I've actually had my soul transferred to both quite a few times, since Orrian's descriptions of the wildlife there match things I've seen pretty well.

Now for the juicy part, how powerful am I compared to other people? The average person is born with 100 mana and 15 mana regen per day, and can increase both by 0.01 percent per day if they expend all of their mana. That means that if they expend all their mana every day for their entire life, they'll have 431 mana capacity and 43 mana regen per day by the age of 40. The problem is that regularly using more than 30 mana a day can have significant health impacts in humans. Most people also don't grind AT ALL since it makes you feel uncomfortable, so they usually end up with about 150 mana by age 40. Constant mana grinding can cause anything from making their limbs unusable to blindness to frequent heart attacks to randomly dropping dead. It also does huge damage to your soul, which can cause you to rapidly lose mana capacity if it breaks. There are soul healing skills that would negate this but hardly anyone has them, since high tier soul healing skills that can be used on others are very rare. Soul healing skills that only affect the user are actually pretty common in anyone with over 500 mana since they're basically required to survive the improvement.

Now, where do the wizards and witches and demon lords come from if improving your mana takes so long? Titles! Having a title DRAMATICALLY improves your mana growth rate, the ease of which you can get skills, and increases the chance of gods helping you out when you're in a pinch. Someone with even a simple title, like the one gotten from singlehandedly saving a village from monsters; "Village Savior", will gain mana at 10 times the speed and gain skills at 20 times the speed. Getting a title at 20 years old when you have 200 mana will allow you to get 296,459 mana by age 40! Unfortunately, expending anywhere near the required mana to grow that fast every day really would kill you, and the time it would take to get the skills to survive it would be too long, so most people with that title end up with around 15,000 mana by age 40 and never improve on that front, instead opting to get more skills. You need a better title to get skills that let your survive high mana expenditure in a short time frame. The best titles for mana and skills are "Hero," "Demon Lord," and "King." Negative titles like "bandit," "thief," and "murderer," seem to be much easier to get than positive titles, and have a higher effect, the downside being you'll never walk into a town with an appraisal station again.

The most popular skills are as follows: among humans, it's fireball. Most children can get it by age 10, and if they don't have it it only takes about 3 years for a title-less person to get. A 100 mana fireball can fry a person dead. It can also be used to cook things, as 100 mana would let you shoot fire for nearly 10 minutes to cook with. The second most popular is "Quick heal" which can heal cuts and scrapes and small injuries in general for about 50 mana, or large injuries like a broken bone for a total of 1500 mana. More importantly, it has a huge pain nullification effect and forces things to heal properly, so they won't get infected or heal in the wrong spot. It takes about 4 years to get for a title-less person.

Elves also like "Quick heal" but prefer "Heater" instead of fireball. It's great for heating cold rooms, being outside in the snow, and cooking, but not for lighting fires or fighting. Heater is more efficient than fireball, and takes roughly 2.5 years to get. Despite the differences in skill preferences, elves and humans only have the difference that an elf can live up to 180 on average and a human will usually die at 90. That is, of course, assuming they don't get sick or killed by a monster. 

Traits are obtained by enduring what they would help you with. It takes about a year of being starved to gain "starvation resistance," which allows you to move your body with free mana instead of your muscles when you are very hungry. The most common traits in fighters are "Penetration resistance," "cut resistance," and "burn resistance." They automatically prevent you from being penetrated, cut, or burned by repelling things that would do those, with force in newtons equal to your mana capacity.¹If you have 250 mana capacity you can stop an arrow shot from a 50 pound bow, according to my research. Remember Briar can give an arrow 5000 newtons of force for a single point of mana, so penetration resistance won't do shit.

Taking into account all that information. I checked my status, and realized there are more changes than I thought.

My mana has increased by a lot.  Apparently every title has hidden specs, and mine gives me a pretty good mana growth rate. It also gives a relatively small boost to the speed I can get skills at, but also a RIDICULOUSLY high chance for those skills to be upgraded versions, though that's only if I need them to be. The exact mana growth rate I have is 0.4.²Briar has been using 10 mana a day for the last 8 years. (They'd been using mana before that too but "Relatively Transcendent" was constantly resetting her mana capacity.) If they had been using all their mana, they would be at 3,491,645 capacity right now (if it weren't for the fact it would cripple their soul), however, they have only been using about 10 mana a day so they have only increased to 329 mana. If they had learned that using more mana makes mana increase faster, they would have done so.

Other notes are that Clairvoyance leveled up, and  the base cost is 1/5 as much per hour now, and 1/5 as much per meter from me. I got the trait "Incredibly long living" because I've lived so much longer than the average life span of a grass, 8 years instead of 42 days, albeit with help from Orrian's magic. It slows down the aging process, and in my case would let me stretch the 20 remaining days of the lifespan of a grass into 5 years. Language learning just makes remember words and rules related to a language you don't know easier.

IsekaiWriter

That's it for the introduction of the protagonist and the explanation of the magic system. I'll be sprinkling in more throughout the rest of the series but for now that's it. Next chapter Briar will go off to do their thing elsewhere and we'll meet new characters. It's honestly where the story truly starts.