Just wow , someday or oneday is a thriller , time travel and has a lot of secrets. I'm not gonna give spoilers so....
1) you'll get a strong and independent FL
2) the love and angst is top notch
3) yep ! There's a creepy psychopath
4) you'll get to see dark theme like depression- suicide, murder, sexual assault and homosexuality
5) staring is a bit slow but,keep patience, from middle arc the real thrill stars and keep the quality till the end
Now the negetive things:
1) the concept is not simple, so It can be confusing but they kept the concept flawless
2) it's obviously not a fluffy romance time travel but based on dark concept so your mood can be negatively affected
3) it's not a happy ending but a angsty parting with open ending.

But still it's a well written and really good drama, 100% recommended for thriller suckers .....