Lost Judgment

To purchase skills, pull up Yagami's phone () and open the Skills app. For this achievement you'll need to unlock 100 non-boxer skills.

Skills are unlocked using Skill Points (SP), which you can gain from pretty much anything - completing missions, playing minigames, fighting, dining, and chugging Hug Bombs. There are a few ways to increase your SP gain:

• Buy the Battle Bonus skills from the Stats tab as early as possible. These will cost 157,500 SP and will make you underpowered in the early game, but you'll thank me later.
• Complete the W. Shichifuku Poppo Squirrel Search and wear the Training Innerwear gear.
• After you've finished the main story, complete the Yokohama Liumang Gauntlet in The Gauntlet. A good strategy for this is to hold and spam in Tiger Style. At the third group of guys, use the Savage Slam Extract and spam to get your EX Gauge back. When that runs out, revert to using +. With the gauntlet done, you can pick up Training Long Pants from either detective agency mailbox. Wear those.
• Buy the Training Band from Ebisu Pawn Kamurocho for ¥78,000 and wear it.
• Buy the Secret Contacts from Kinka Pharmacy for ¥15,000 and wear it.
• When eating at restaurants, look for food with a green star in the top-left corner. These will temporarily boost your SP gain. The skills Lucky Gourmand (13,100 SP total) and Auspicious Gourmet (Complete Side Case 31: Squirrels Just Wanna Have Fun, started just outside Seiryo High School in Chapter 5 or later; 20,000 SP) will help with this.

Your performance in battle matters! You'll get bonuses based on how well you do. I recommend defeating at least one enemy with every style in every battle, if possible.