Ah, so that's the storage gaps. There seem to be so many gap-types that I didn't know which one does what, and I was too lazy to look up the kanji ;-P
I learnt most of them through experimentation.
There aren't many (variety of) HP ones. Most of the time, I just relied on the HP rengeration from moving around instead.
...all the potions are notable for their own purposes. The ones that I found useful were:
加速薬 - Spd+ (doubles)
怪力薬 - Dmg+ (doubles)
目薬 - Reveals traps
and invisible units
緑茶 - HP +20; at full HP you instead get Max HP +1
玉露 - HP +100; at full HP you instead get Max HP +3 (why would you do that with this one!?). This also heals the ailments such as slow.
The ones that I suggest you don't drink unless you're desperate:
毒薬 - Poison; -1 "ちから" (this roughly translates to Vigor; which is a factor in determining damage dealt). If you have an Antidote (解毒薬), then it's fair I suppose. You reduce hunger at least by drinking both.
混乱薬 - Confusion Drug; Confusion. Throw this at enemies or sell it.
爆薬 - Explosive; :V
睡眠薬 - Sleeping Drug (loc: Pill); Sleep. Throw this at enemies or sell it.
Then, there are these:
しあわせになれる薬 - Happy Drug; +1 Level
ちからの薬 - Vigor Drug; +1 Max (and current) Vigor
どくだみ茶 - (?? Tea); +5 Max HP
みず - Water; Personally I would just drink it to reduce hunger by 5%. Don't really know any other uses at this point. Might consider throwing it at Mokou at some point.
I could rearrange this into order if you wish. Though, they are somewhat in order at this point.
Spell Cards
博打「エスポワール」 - Gambling by Rock Paper Scissors. Double or nothing. Honestly, I wouldn't bother taking the risk.
厄除「サーディーンヘッド」 - Enchants equipped items to not get hit by curses (which reduce their effectiveness / curses them)
名付けて「越後ショート!」 - Turns selected item into food.
Apparently does not work on "Tags" or Gaps.
増大「ピロルスの解放」 - ? I think it increases the space of a Gap by 1.
夢符「二重結界」 - A.K.A. "Duplex Barrier". Hits all squares around you. Does a lot.
幻惑「アンキャニーシャイン」 - Confusion to all (visible?) enemies.
強化「荒御霊」 - Enhances (equipped) Weapon. Also uncurses.
御祓「カーネルサルベージ」 - Uncurses. Forgot if it was only the equipped or entire inventory or whatnot. Didn't really use it too often.
照符「ブックオブライト」 - Book of Light. Reveals entire floor except for invisible units / traps.
忘却「ニューラライザー」 - Sleep to all (visible?) enemies.
硬化「幸御霊」 - Enhances (equipped) Armor. Also uncurses.
神霊「夢想封印」 - A.K.A. "Fantasy / Dream Seal". Hits all visible units. Moderate damage, about 25 damage. Good for 30F, except for one tiny problem...
These Spell Cards are in order. That's not the entire list. There are other Spell Card exclusive to the second dungeon for instance. Or, ones that I missed out on.
Oh, there's also a gap that heals your HP to full when you put items in. Those are rare and are only really useful at the end though.
And to get it out of the way, you can't place gaps in gaps :V
EDIT: Forum font is squeezing the text together a bit; take care of that.