They're actually "Mana Refill" and "Mana Gain". Chakra Shoes is the JP name for Mana Refill.
"Mana Refill" basically restores an amount of MP every time a phase of kagutsuchi changes. "Mana Gain" gives you MP at the end of every battle. In other words, "Mana Gain" is better if you get more encounters than changing phases. Since that's not the case unless you are using "Riberma" to increase your encounters, you usually find better use for "Mana Refill", since on average, the kagutsuchi changes phase 2-3 between random encounters, and thus gives you more MP for the next battle.
Basically, go with Mana Refill if your demon uses magic in random encounters. It's a good replacement for "Mana Drain" on your Demi-Fiend, and well worth it until very late into the game if you don't rely on a demon like Daisoujou to be your reliable "battery". --- Currently playing: Shin Megami Tensei: Devil Summoner - Raidou Kuzunoha vs. the Soulless Army (PS2), Dissidia: Final Fantasy (PSP)
There is mana refill which fills outside of battle and (forget name) that refills during battle. I like mana refill better as battles are over pretty quick anyway. I guess the other could be better for bosses, but you could always use a mana item instead.
--- - My Games - http://backloggery.com/IronMonkey008 - My Books - http://www.goodreads.com/IronMonkey008
Mana Aid refills your MP after battle. Mana Gain increases your max MP by 20%. --- I hate my job, all of my rich friends. I hate everyone to the bitter end. Nothing turns out right, there's no end in sight. I Hate My Life.
Mana Refill gives mana every moon phase change. Works with Estoma. Mana Aid gives mana after each fight. Works well with Riberaman. Mana gain/?/surge gives 10%/20%/30% mana. Makatora transfers 10 mp from one demon to another demon. Mana Drain is a 100% accuracy MA drain attack. Life Drain is not a 100% HP/MA drain attack.
And Victory Cry, which fully recovers your HP and MP after battle. Which includes backups (If you win and then reinforcements appear, demons with Victory Cry recover HP and MP for reinforcements... Mana Aid does the same). --- Currently playing: Shin Megami Tensei: Devil Summoner - Raidou Kuzunoha vs. the Soulless Army (PS2), Dissidia: Final Fantasy (PSP)