It took a while before I finally realized what was happening.

  I don't know if my assumption is correct, but I think I know what I am doing.

  I can go to alternate dimensions!

  After panicking for some time and then actually investigating what's happening, I came to that conclusion after managing to mimic the same feat as what I did this morning.

  So when I tried to focus on doing the same thing again, I felt a strange energy being sucked within my body while my body got yanked to a dimension comparable to my original surroundings. This mysterious energy seems to be connected to my mind because as I feel it leave my body, it gives me a headache.

  I decided to call this mysterious energy Mana until I find a better term for it.

  Anyway, staying within a dimension saps my mana away. If I return to my original dimension, the gradual loss of my mana will stop, and I can recover it after resting for a while. I don't know how much mana I actually have, but personally for me, I think I have a small amount of it.

  I can only stay in an alternate dimension for ten seconds before my headache gets worse. If I try to force myself, my body will just return to my former position before I got to the alternate dimension. I didn't notice that at first because I sat in the same place that I am sitting on before I unintentionally yanked myself into the alternate version of my world.

  I can choose whether to leave my world on my own. I can also choose whether to come back to the same position I am standing in the alternate version of this world or return to where I started. I think I can use this feature to escape difficult situations.

  Whenever I use my power, I jump into an empty alternate version of my surroundings. This is just based on my own observation, but I think every living being is exempted from my jumps to the alternate dimension. Only non-living objects, like the water bottles or the buildings themselves, were copied when I used my power.

  This feature is quite useful. In fact, it is important for my survival!

  With this power, I can just grab an alternate version of an object and bring it to this world, essentially creating more resources for myself out of nothing!

  But it is not that simple. First of all, I can only bring alternate versions of these objects by grabbing them. If my hands aren't touching an object before I jump back to the original world, it won't come back with me. At the same time, even if I'm simply touching an object, it shouldn't be part of the ground or the surroundings. I tried touching the building I am standing on, and it doesn't really make another version of this high-rise apartment even when I return back to this world. I also haven't managed to copy the door or the faucet in my room because they are part of the building itself, not really separate at all.

  But I can make duplicate versions of the cabinet and the drawers despite not being able to carry them so long as I change their position and then keep my hands on it before I jump back to the real world. Essentially, I can duplicate objects that aren't bolted to the ground or the building I am standing on!

  Even with that mechanic, I can't really abuse it too much. I don't like the headaches I am experiencing whenever I stay in the alternate world. I can feel that mental exhaustion within five seconds since using my ability, so I essentially have half the time than my exact duration if I force myself. There is also a cooldown of some sort with my powers, as I can't constantly keep using them or else the rebound on my head will double.

  I tried spamming my ability without staying in the alternate dimension for a second longer, and my headache got worse. I was forced to recover from my headache for a longer time than when I simply used it sparingly throughout my test. It hurts, but it's a good thing I found out the limits of my power.

  So anyway, my mana doesn't instantly recover on its own. I have to rest for at least a minute before I recover fully. If I just keep scraping all of the mana within my body, it would take me an hour being incapacitated.

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  Can't let that happen in the middle of a monster-infested street!

  So I am inside my room, surrounded by a lot of backpacks filled with water bottles, eggs, and instant ramen cups. I put them all in backpacks because, limiting myself within five seconds in the alternate dimension, I got this ingenious idea to just carry a bag filled with my rations instead of carrying them by hand one by one.

  It's already nighttime when I'm done with my experimentation. Despite the pitch-black darkness on the outside, my room is illuminated as if electricity is still working in my house because of the power lamps set around certain parts of my apartment room. Each power lamp can last up to 16 hours, and I don't have to worry about their power anymore because I have a lot of solar chargers with me.

  I've also charged duplicated versions of my phone, which I've already reformatted so I could use them as disposable phones, and flashlights, as I think these would be important for my survival, among other things.

  Now I'm just sitting on my bed, sustaining myself with water only. I need to find any battery-dependent appliances like cookers and heaters if I want to cook the eggs or eat my ramen cups. With only five seconds' duration in my stay on alternate dimensions, that is basically impossible. I don't want to leave this room!

  I wonder if there is any way for me to extend that duration. Is there something I can do to increase my mana capacity?

  "... Ugh, I feel hungry..."

  I should have rationed my biscuits even when I'm sick! I'm not used to sustaining myself with water only!

  I can only endure the grumbling in my stomach as I continuously drink water until I fall asleep.

  "Okay... this can't go on!"

  I can't endure this!

  Sustaining myself with water only? No way!

  Even if I live unhealthily, I still want to eat something!

  I'll be fine even if I only have egg and cup ramen. I just need something to eat!

  It's been two days since then, and I can't take this anymore!

  "... But, even if I say that..."

  ... No, I don't want to leave this room. Not unless I manage to extend my time on the alternate dimensions!

  But I don't know how to do that. I've tried frequently using my power, even pushing myself to stay for ten seconds before I got forcefully yanked back, but I still haven't felt any improvement with my powers!

  I still have the same mana capacity, and the duration of my stay in the alternate dimension stayed the same!

  Usually in apocalypse novels, people have this cultivation-like progression in their power system where they can get stronger by simply meditating or using their powers repeatedly. If that doesn't work, then I don't have any options left!

  "... Wait, there is that one trope..."

  Oh right, I almost forgot. Another trope to become stronger is defeating the monsters in the apocalypse, and in extreme cases, even eating whatever dropped from those monsters!

  ... Should I try hunting monsters?

  If I recall correctly, it's not just zombies who emerge from this apocalypse. There are also images and brief clips I've seen on the internet that show gigantic creatures emerging from the ground. Can I really hunt those monsters?

  A normal protagonist will think they have no more options left and leave their base, trying to find opportunities for themselves even if it is dangerous.

  But I'm a coward!

  If I am forced to hunt monsters anyway, then I might as well find ways to do that safely!

  But how to do that? I don't want to leave my room. The only way I can hunt is to... Right!

  I looked at the closed curtains of my window and opened it. Beyond is a city still rife with unknown creatures out there. Piles of reddish bulks and brownish mountains of something were scattered on every street. Inhuman silhouettes moved on the streets, still looking like ants in my eyes. I also noticed a gathering of those silhouettes on some of those reddish-colored piles.

  I don't have any ranged weapons to deal with any monsters, but I do have a lot of stuff that can kill if thrown.

  I look at the mountain of knives just piled on top of my dining table as a simple and silly idea forms within my mind.

  It won't be efficient. I'm sure it won't even hit those monsters with its sharp point even if I throw it randomly, though regardless, it is the safest option!

  I take one of the knives and then, like casting stones on the river, I throw it in the air without regard to where it will go.

  Without waiting for the results, I took a lot of my knives and then simply threw them repeatedly in the window. I can just replenish my knives with my powers, so I essentially have infinite knives in my hands.

  And so, I keep doing that all day. Not knowing whether I killed something or not.

  It took a while before I suddenly felt it. A warm sensation suddenly entered my body and made me feel refreshed. The warm sensation of my mana seems to have expanded, and I felt within my heart that my magic capacity has increased.

  Immediately, I hopped into an empty alternate dimension, and then after a while, and at the same time, timed myself with my phone. After I felt my headache getting progressively worse, I stopped and looked at my phone.

  "... Twelve seconds..."

  The duration of my dimension hopping got extended by two seconds!

  "... Hehehe!"

  Great! So I don't have to eat anything weird from those monsters. I simply have to kill one!

  Then, my next action should be obvious.

  "I have to kill more!"

  I've already checked, and I haven't seen any humans at all on the streets. So whoever I might have killed was surely not human. Killing monsters that threatened my life doesn't concern me!

  All that matters is that I survive!