I'm almost done with this game after 60 hours (at the end of my 2nd playthrough) and I'd like to get 30k bonus points. Right now I'm stuck at 25k. Most of the achievements I see in that room aren't translated. Working on the 1 million steps achievement as well.
Are there some other easy ones I could crank out in a short amount of time? Realistically I just need 2 thousand. I've gotten all the party members and beaten all the super bosses. But I'm pretty close to just giving up on ever beating the Demon Lord if it requires a massive time investment on top of what I've already put in.
You're at the point where you can buy both the "keep your armor" and the "keep your level" options at the new game+ shop. This basically lets you trivialise 90% of a run, as you start with all your end game gear save spear, can go straight for the dungeons that get you ships and crest slots, kill the super bosses (preferably with the exp multipliers active for the best ones), and then either try to kill or go suicide at the demon lord to reset your run again. you get extra ng+ points just by virtue of doing more runs, and as your level rises you'll easily hit the Attack/defence/hp achievements for ng+, giving you even more.
This actually makes levels relevant to your stats again as well, in my case i'm 30ish hours into the game, am on ng+7, level 173,000. That level alone gives me 1.7 million hp, 680k attack, 340k defence even before you add gear... you get tons of stats once you can maintain your level between runs. Note that i get literally 99.999% of my exp from 2 specific fights: the Ancient Being and Omega. These give 21m and 30m exp respectively, by far the most of any mobs. The reason why only these 2 matter though, is because each run you can buy only 2 of the LV11 exp boosts, which cost rainbow coins. I use them on these fights to multiply exp 50fold, which gives me like 10,000 levels in a single fight.
And since you don't need to grind for gear and can skip most dungeons, the time a ng+ run takes is less than half an hour.
I actually wrote down my ng+ schedule:
Go town 1, grab heal skill > Go town 2, get skill book, talk to old guy for skill temple rumours > go to town 3, get the 1st boat > go to skill temple, nuke boss, get skill book
Clear the tower > visit the king for crest and 2nd boat > get volcano rumours in snow town, clear snow dungeon for floating city gem
Clear floating city for skygem > return to king, go scientist with skygem for airship > go ruined town for pick > clear volcano for inheritance
Town 5 for fairy pool rumours > go fairy pool to fix inheritance > superboss hunt the first 3, leave omega and Ancient being for now > use rainbow coins from the boss kills to buy LV11 exp boosts
Kill omega and ancient being, using exp boosts > sell all your valuable junk > go skill temple, buy stuff > visit home to unlock demon lord castle > fight demon lord
This should take less than an hour, since most dungeon clears are literally just running to the boss and one-shotting them with whatever they're vulnerable to. Even Omega goes down in 2 turns, I actually spend more time waiting for skills to cooldown between superbosses than I do actually fighting them.
This is only possible if you used the "keep armour" ng+ option, as that lets you completely skip grinding for gear. You also need "keep level" so that you get the benefits of the boss exp from omega and ancient. these are the 2 most important ng+ options, prioritise them over everything else.
I'm at ng+7 after 32 1/2 hours, and have beaten the demon lord solo on the last run. The key really is keeping gear to skip the gear grind, enabling speedruns, then using speedruns to farm exp off Omega and Ancient being. once you're level 100k+, demon lord should be doable. if not, just farm another 30k levels a run and try again.
Edit: Just want to add something; this is why almost everything in this game is cleverly gated by enemy difficulty, rather than needing to beat a specific dungeon/boss. Once you have gear or levels from a previous run, you can elect to simply skip whole portions of the game in order to get to the parts you still need to do, like the demon lord solo. The only real exceptions are stuff that unlocks crest slots, travel methods, or prerequisites to those things.