After clearing Chapter VII of the main story, you can access Aniki's Gym, where you can obtain materials to level up Soldiers in the Training Field. There are six different gyms with 12 levels that rotate daily and give different training materials. Each gym has 12 levels of increasing difficulty from Lv 15 to Lv 70. Higher levels have a higher chance of dropping rare training materials, which are a major bottleneck in levelling up your soldiers. Each level costs 20 stamina to challenge alone or sweep and 16 stamina to challenge with another commander. You will also get a bonus for the first two times you challenge Aniki's Gym levels every day so make sure to complete or sweep these levels on a daily basis.
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